Infinity +1 Sword

By the time you've earned this, there won't be any evil left to use it on.

"Final Fantasy games give you a choice: you can either spend forty hours playing underwater foosball or watching chocobos screw or whatnot, which eventually gives you your ultimate weapon so that you can defeat the final boss pretty handily. Or, you can spend those forty hours actually fighting the final boss. It's up to you. You want a quick game, go play pinball."

— Lore Sjöberg, The Book of Ratings

This is a weapon, spell, special attack, etc., that is not only the most powerful of its kind in the game (at least for its respective player character(s)), but its power is matched by how hard it is to acquire.

So you'll never get it by just sticking to the game's main story. If you want it, you've got to put the plot on hold and embark on a five-hour sidequest! That, or find the enemy that Randomly Drops it (which will likely be a Metal Slime or Boss in Mook Clothing from the Bonus Dungeon, and the drop rate may be just 2 percent, or 5 percent with a Random Drop Booster).

One would think that the time needed to finish the subquest could be better spent on Level Grinding, so the Infinity +1 Sword is often more useful because it has other associated stat bonuses, unique to the character, rather than merely being stronger than other weapons (or so strong that even leveling up can't give you that kind of strength). Also, it's unlikely the dungeon the sword is in will be uninhabited; in fact, the monsters there tend to be very XP-rich anyway.

Sometimes the sword has not been forged yet — if that's the case, you need to find the Ultimate Blacksmith so he can make it for you.

If the bosses you need to defeat for it aren't optional, that overlaps with Last Disc Magic.

If it's only possible to obtain this once every challenge in the game has already been overcome, it's also a Bragging Rights Reward. This can also be if it is Level-Locked Loot (if your level has to be so high that you could beat even the final boss with a lesser weapon).

As noted, this doesn't actually have to be a sword. The reason why, in most games, it does happen to be a sword is covered by the trope Sword Almighty.

A Sister Trope to Infinity +1 Element (this applied to Elemental Rock-Paper-Scissors),

Compare Penultimate Weapon, Sword of Plot Advancement, Armor of Invincibility.

Also compare Olympus Mons, for when the sword in question has a conscious mind of its own.

Compare/Contrast Infinity -1 Sword (in that it's also powerful, but much easier to get). Compare/Contrast Awesome, but Impractical for some items, as they may be an Infinite +1 Sword, but suffer drawbacks that make them difficult or impossible to reliably want to use.

Do not confuse with More Than Infinite.

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Examples:

• Video Games

Non-video game examples

Anime & Manga

• The sword Sayafushi from Bleach was a failed attempt to make a ultimate sword. The problem is that the sword is too perfect. The sword's perfectness makes it impossible to build a sheathe capable of holding it so it has to be suspended in special tank of jelly when not in use, and it is too dangerous for anyone other than its creator to wield.
• Excalibur of Soul Eater is the most powerful weapon in the world and is also what inspired the creation of Demon Weapons, and unlike Demon Weapons, which can only be used by someone the weapon can synchronize with, he can be used by anyone. Some of the known abilities he grants his wielder are Heavenly Wings, light speed movement, the ability to slash everything with gigantic explosions of golden fire, and cutting open dimensional portals. But almost nobody would ever want to wield Excalibur because he is an obnoxious egotistical lunatic.
• Sword Art Online:
  • In the Light Novels, the <<Holy Blade Excalibur>> is considered the strongest weapon ever in the VRMMORPG Alfheimr Online. The only way to get it is by moving through all of the impossible dungeons of Jötunheimr, home to the Evil-God Class monsters. One Evil-God Monster requires a party of more than 20 people with the best of equipment just to stand a chance in fighting them. The first time we see it, however, is when Kirito uses the Master Console to summon Excalibur. In a supreme insult to Smug Snake Sugou, he gives him Excalibur while Kirito sticks with his normal sword. Kirito still brutalizes him, ending with cutting Sugou's head off and impaling the thing on his sword... with the Pain Restrictions completely off. He got off easy.
  • A later story (adapted into a short 3 episode arc for the anime) covers Kirito and his friends doing the dungeon dive for Excalibur. However, their quest is complicated by the in-game plot, inspired by Norse Mythology, which turns the quest into a race against time to clear the dungeon and claim Excalibur before Ragnarok is set off in-game.
• Infinity +1 Swords are apparently a dime-a-dozen in the world of Thunderbolt Fantasy where they are called Shen Hui Mo Xie (Weapons of Divine Teaching), with clans of monks called Hu Yin Shi (Seal Guardians) trained from birth to protect various such swords throughout the land. However, the Tian Xing Jian (Sword of Divine Retribution) is said to be the most powerful of these swords, as it is said to have been the only one that was powerful enough to slay a demon god centuries before. This makes it the target of Mie Tian Hai who wants it for his own selfish reasons, spurring the plot of Season 1 when he launches a raid on Dan Heng and Dan Fei's shrine. The only person in the world who doesn't think the Tian Xing Jian is as important as everyone makes it out to be is Shang Bu Huan, a visitor from a foreign land unwittingly thrust into the plot of the theft of the sword; even when he sees part of it kept by the sole survivor Dan Fei, he is still suspicious of its power. He turns out to be right when it is revealed the sword didn't slay the demon god but sealed it away in the grounds beneath the Dan clan's monastery. And he should know because he has the Sorcerous Sword Index, a magical scroll holding thirty-six weapons far more powerful than the Tian Xing Jian that he has stolen from various wizards, sages, and ne'er-do-wells from his homeland to prevent them from being used for evil. One spell cast by the Absolute Phantom: Jie Huang Jian is enough to throw the aforementioned demon god into the farthest reaches of outer space.
  • Season 2 digs deeper into the Sorcerous Sword Index when Shang Bu Huan's old foes Xie Yingluo and Xiao Kuang Juan arrive from Xi-You to steal it from him, with two more of its dangerous swords being revealed. The Night of Mourning is apparently incapable of actually injuring any human, but one touch from its blade turns anyone into the wielder's mindless puppet. And the Seven Blasphemous Deaths is sentient and uses its magical powers to compel people to want it for themselves; its wielder wants nothing more than to continue to wield it and protects it from all who come near, and anyone who gazes upon it is feverishly drawn to steal it for themselves only to meet their demise and have their spilt blood empower the sword and its wielder. And there are still 33 more weapons we don't know about.
    • The movie Thunderbolt Fantasy: Bewitching Melody of the West shows us the Dark Phantom: Wanshi Shen Fu which has the power to split the ground apart. Shang Bu Huan and Mu Tian Ming steal it from the Emperor of Xi-You and then use it to escape from Xiao Kuang Juan and his soldiers trying to retrieve it and Lang Wu Yao. Later, Shang Bu Huan shows Lang Wu Yao that the Emperor's army previously used it to commit an act of genocide against a people he was seeking to subjugate, with part of the landscape now a cliff leading to the sea.
• In the "Waking the Dragons" arc of Yu-Gi-Oh!, Yugi faces Divine Serpent Geh, a snake that has infinite attack, in a duel where both he and his opponent have 0 life points (yes, it's weird). He loops the attack of two knights making them have infinite attack, then combines them, to make one knight with an Infinity +1 Sword — literally.

Gamebooks

• In Beneath Nightmare Castle, the Trident of Skelos is one of the mightiest weapons ever to show up in a Fighting Fantasy book. Unfortunately, it's broken in two pieces and it's fairly late when you can connect both pieces, so there's not many enemies left to skewer with your new weapon.
• Blood Sword: The titular Bloodsword itself has split into 3 different pieces. You finally recover and combine the pieces only to have it stolen. The earliest you can use this sword is in the final fight of the 4th book in a series that's 5 books long. Which is too bad as it's the most powerful weapon in the game by far and uniquely it can One-Hit Kill (though restricted to the undead and the deathless).
• Lone Wolf: The Sommerswerd, the Sword of the Sun. You get it in the second book, which seems somewhat game-breaking, but its later awesomeness makes up for it by far. To get its full potential out, you require certain Kai skills during that book: Sixth Sense gets you a description about how the sword improves your Sixth Sense, and having Weaponskill (with the sword) gives you the "extra" CS bump of + 10 instead of + 8. Some of the later books have weapons that are either even stronger than your solar blade (e.g. the Death Staff) or don't create near as much attention when trying to deal a preemptive strike (e.g. the Ironheart Broadsword). For the most part, however, the Sommerswerd is the best you're going to get, due to being unable to keep the more powerful weapons at all.
  
  The Prisoners of Time and the infamous Chaos Master deserves special mention. (The other foe where the Sommerswerd is a handicap is Zakhan Kimah, but there are ways around this.) As mentioned before, the Chaos Master will be a lot stronger if you fight him with the Sommerswerd than if you don't have it and are able to obtain the Ironheart Broadsword. The problem is that if you don't have the Sommerswerd (you can't keep the IB), the LAST battle, a doubleheader against the condemned Sommlenders and Vonotar, will be nearly impossible to survive. Any way you look at it, 1) a mighty sword of the gods being weak against two enemies out of the dozens you'll face doesn't come close to justifying doing away with it and 2) completing The Prisoners of Time by ANY means is an Infinity +1 task regardless of what kind of hardware you have.

Fan Works

• In A Special Kind of Magic, Naofumi explicitly uses his knowledge of his homeworld to create these, by first copying Captain America's shield (and giving Sam a good scare while doing so), and then gaining Raphtalia a sword with the same powers as Mjolnir!
• Child of the Storm sets up Ván, the legendary sword of Frey, as this - forged of uru and vibranium, with all kinds of magic poured into it, it was capable of countering and absorbing Phoenix Fire. Unfortunately, a) since it was a literal last resort, there was never any time to record how it was made, let alone replicate it, b) despite people having searched for a million years, no one's ever been able to actually find the damn thing - something not helped by the fact that it has the most Boring, but Practical design imaginable.

Film

• Kubo and the Two Strings has Kubo going on a quest to find the Sword Unbreakable, the Armor Impenetrable, and the Helmet Invulnerable to defeat the evil Moon King. But it turns out that even while wielding them, Kubo is not simply not strong or skilled enough to defeat the Moon King and ultimately has to defeat him with a different means.
• Marvel Cinematic Universe:
  • In Avengers: Infinity War, Thor, Rocket Raccoon and Groot help Eitri the Dwarf (creator of Mjolnir) forge one of these to give Thor a chance against Thanos. Eitri isn't exaggerating when he says this will be the greatest weapon he'll ever forge; the resulting Stormbreaker allows him to wound Thanos even after he obtained all six stones and deflected a blast from the Infinity Gauntlet.

Literature

• The swords used by Dragon Riders in The Inheritance Cycle, are forged from Thunderbolt Iron, making impossibly sharp, and enchanted so that they never dull. Each one is an Ace Custom, and specially made by the elves greatest smith to fit one Rider in particular.
• The Named Swords in The Licanius Trilogy can kill mortals at a touch and drain Essence from their surroundings, making them completely broken in normal combat. Licanius, the series' namesake, is the only thing that can permanently kill immortals.
• Magistellus Bad Trip has the Over Tricks, or Inheritance as they are collectively known. These are pieces of equipment once owned by the legendary player known as Criminal AO. All of them have been customised to the point that they literally break the laws of physics in the game.
• The Apprentice Adept series has the Platinum Flute. While it lacks the ready utility and ease of use of fellow Amplifier Artifact, The Book of Magic, it grants the user access to far greater magic. Magic that can literally move the world. But only two types of people can use it at anywhere near full power: An existing magic user (It can enhance an Adept's power to literally unstoppable levels) and a master musician (only the VERY VERY best can access the Flute's higher range of powers. One who can becomes Phaze's strongest magic user, period).

Live-Action TV

• Kamen Rider Ex-Aid is video game themed, so naturally this trope ends up being a major plot point. Kamen Rider Chronicle, the Deadly Game every Big Bad builds their plan around, is supposed to be a grueling sixteen-year Boss Rush with the reward being to become the impossibly powerful Time Master Kamen Rider Cronus. However, the Big Bad executes a Sequence Breaking method to become Cronus immediately by putting in his sixteen years of training before the game actually existed yet, meaning he doesn't have to fight any of the bosses.
• Kamen Rider Saber has two Infinity + 1 Swords: one for combining all of the sacred swords that make up half of the powerset of Riders in Saber, and one for combining all of the magical storybooks that make up the other half. By the end of the series, the title character gets his hands on the ultimate sword, while the Big Bad gets the ultimate book.
• Stargate-verse
  • The Asgard plasma beams acquired near the end of the series count. For years, the Tau'ri ships were only armed with rather weak railguns and easily-interceptable missiles, making them rather underwhelming in combat. The 'quest' involved to obtain these upgraded weapons involved travelling to the Asgard homeworld in another galaxy and narrowly escaping an Ori attack, as well as outrunning the self-destruction of the Asgard planet. When the Asgard finally realize that they are completely doomed as a race and give all of their remaining knowledge and technology to Earth, the Odyssey obtains these weapons which are capable of taking out Ori battleships (which were previously shown to be nigh-invincible) in a few shots. Notably, this only takes place in the very last episode of SG-1, although the weapons get more use in later seasons of Atlantis. The only thing that was ever shown to stand up to them was the Wraith super-hive.

Puppet Shows

• Pili Fantasy: War of Dragons: Everyone considers the Dragon Bone Sacred Sword to be this. But the truth is it's got room to be upgraded with more elements to be made much stronger.

Webcomics

• All kinds of crazy powerful weapons exist in Homestuck, but the one that fits this trope the best is Dave's sword Caledfwlch^note This is another name for Exalibur, and is pronounced "Cal-ed-Fool-ch". Obtaining this sword required going through a complicated sidequest. Dave first finds the sword stuck in a stone which he is unable to remove it from, so he gets just the bottom half of the sword by breaking it. The broken half is then used to make a new sword called Royal Deringer, which Dave also ends up breaking. Much later, the broken Royal Deringer is combined with a magic cue ball to recreate Caledfwlch. Caledfwlch is revealed to be one of the only weapons capable of harming the otherwise completely immortal Big Bad, Lord English. During [S] Collide, Dave shows just how powerful Caledfwlch is when he uses it to break the Unbreakable Katana and decapitate three people, one of whom was Lord English's avatar in one stroke.
• +99 Reinforced Wooden Stick: The protagonist is a newbie in an MMORPG that is somehow able to upgrade a simple wooden stick to level 99, something that should normally be functionally impossible by the game’s mechanics. The stick can now split continents and One-Hit Kill swathes of players with one swing.

Web Original

• The Adventure Zone: Balance has the Flaming Raging Poisoning Sword Of Doom, an deliberately super-overpowered weapon submitted by an eight-year-old fan of the show. Griffin decided to include it in the Fantasy Costco as a shout-out to the fan, but to ensure that the heroes would never actually get to use and abuse its power, he put an unattainable price point on it. He underestimated Taako, however, who manages to abuse a Chain of Deals to ultimately con Garfield the Deals Warlock out of it.

Western Animation

• One episode of Ben 10 had one of these as the MacGuffin, an ancient sword that is the ultimate weapon, much more powerful and dangerous than Ben's omnitrix. The villains end up reaching the sword first, but it immediately crumbles into dust because despite being the ultimate weapon, it was thousands of years old and not immune to aging.
• Ben 10: Ultimate Alien had an arc expositing the origins of the Forever Knights that involved another legendary sword. One wielded by their founder Sir George against an Eldritch Abomination that took the form of a dragon. It was created by Azmuth as an ultra advanced device capable of manipulating the laws of physics and misuse in the wrong hands once blew up a planet.

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