History Matters
In many works of medieval historical fiction, medieval fantasy, or ancient historical fiction, the hero uses a sword as a primary weapon. This is regardless of whether a warrior of the culture in question would actually be likely to carry a sword at all.There are valid reasons for this trope. In Western culture, especially Northern and Central Europe, the sword is seen as the symbol of chivalry, nobility, and power. The straight-bladed Middle Ages knightly sword with a simple hilt and crossguard also strongly resembles a cross, adding religious significance to the weapon. But even moreso, in Japan, the national religion, Shintoism, often depicts the sword as an object associated with divinity. The founding myth of Japan centres on two gods (Izanagi and Izanami) dipping a coral blade into the ocean before stirring it to form the archipelago. In feudal Japanese society, specifically the Edo period of the 17th century, only the samurai class were allowed to carry two swords with them during peacetime to show their noble status. Thus, the huge significance swords played in many cultures are often valued as prestigious weapons for the combatant to use, especially in the battlefield. However, in a battlefield scenario, this wasn't always the case.
Historically, spears were vastly more common weapons than swords. In many ancient and medieval European cultures, spears or other polearms were the primary weapons of most warriors, common or elite. Axes were also quite common, particularly ones that were long enough to count as polearms. Both spears and axes were cheaper to make than swords, requiring less metal, and were also extremely effective in skilled hands. Maces and warclubs were also common, but less than spears or axes. As armor and warfare continued to develop, warhammers became more common specifically to counter armor.
This is not only limited to Europe, however. This applies to many other cultures, including Japan. Historically, the samurai started off as cavalry archers, so bows were their primary weapon, rather than the sword. As Japanese warfare evolved, the samurai relied on many other types of main weaponry like naginata polearms, yari spears, and kanabo clubs. Ultimately by the mid-16th century, Portuguese merchants arrived to Japan, and the samurai were able to get a new weapon technology that can shape warfare in their terrain completely: the arquebus matchlock guns (tanegashima, as they call it).
The sword in both medieval European and feudal Japanese warfare always served a role as a sidearm. Only if the combatants have their main weapons become lost or disabled in combat, would they rely on the sword as a last resort weapon. Otherwise, warriors from both cultures would never rely on the sword as their primary weapon, as they are only limited in use to close range combat in the battlefield.
Another reason not to use a sword is that they were often prohibitively expensive throughout history. As mentioned, any spear, blunt force, axe-type weapon, or even bow and arrows were far cheaper. So when the Hero is a Farm Boy, it's extremely unlikely that he'd have the money to buy a sword or for his relatives to pass one down to him. Of course, he might have received one for a host of reasons, all boiling down to the fact that he's The Hero, so he'd better have a sword.
On the other hand, it is possible to exaggerate how rare and valuable swords were, when in fact this varied quite a bit over time and geography. In early times when the metal and technology to make swords was rare, such as in Migration Era Europe after the fall of the Roman Empire, only aristocrats could afford them and they were often made with pattern-welded blades or jeweled hilts. As technology and production capacity improved, however, they became much more widely available in a variety of different qualities. In the late middle ages or Renaissance, a finely made and decorated sword for a king might cost more than a commoner's house, but there were also plain mass-produced swords and cheap old ones that a poor person could acquire for a couple of pence. For instance, the short Roman Gladius was issued to every man in the Roman Legion as a sidearm — and there are a lot of men in the Roman Legion. To give a comparison, there is no one price for buying a car in the year 2019, because it depends what kind you're getting. You can buy a new Lamborghini for $200,000 if you're super rich, but there are also $20,000 cars for the less wealthy, and you could get one with a lot of miles and no warranty for $2,000. Compare that with 1907, when there was no mass production of cars and only the obscenely rich could afford a car at all. It is not unrealistic for a poor person to have a sword if it's appropriate for their level of wealth in the context of the setting, but you have to do your research.
Another reason that swords were associated with high status, and thus heroes, was that many societies made owning a sword legal (and sometimes required it), but severely limited where and how you could wear it. Thus, anyone who could walk about armed with a sword in town and not be stopped by the local law was clearly no one to take lightly. After all, they were so high status that they could walk around town with a sword and not be bothered by the local officials! Of course, high status and high character were often conflated; notice how words like noble and high-class imply a high character as well as high status, while vulgar and low-class associate low status and low character. This trend continued into the armies of the late Renaissance and beyond, where officers were gentlemen of high class and typically carried a sword, while the common grunts were impressed from the lower classes and usually not given one.
Perhaps another reason why swords are often valued as high status weapons can come from the divine status it conveys. While this can partly be due to how the sword has some religious connotations in Christianity, it mostly stems from Japanese culture. As mentioned, Shintoism depicts the sword as a sacred, divine object meant for warding off demons or evil spirits. Thus, Japan historically, maintained a very deep spiritual custom of the sword and sword-making, even moreso than Europe. When Westerners, especially those who visited Japan in the 19th century, discovered this deep spiritual custom of Japanese sword-making, they never fully understood the meaning behind Shintoism, let alone how this religion shaped the sword-smithing traditions. Thus, it is not uncommon to depict the sword possessing magical divine properties for the hero to dispel evil or darkness.
Practical Reasons
Even if rarity is ignored, there's some degree of logic for having sidearms being iconic of an Action Hero, even if other weapons are much more commonly used: Swords and handguns are (realistically speaking) probably the most convenient close-quarters weapons in their respective timesnote , so just about everybody who had access to such weapons has some training in armed combat; they also carried sidearms in places where primary arms are too powerful to be acceptable (such as when they were far from the battlefield).And, frankly, swords are comfortable to wear and unencumbering. A sword scabbard is a handy way to carry the weapon and keep your hands free. If you had to walk around with it every day, what would you want to carry? Even in the medieval era, the vast majority of a person's life wasn't spent fighting; it was spent working, visiting friends, in sports, in games, eating, traveling, sleeping, studying, and shopping. It was spent living. If you were high enough status to go about your business armed in the pre-Industrial eras, nothing else combines the convenience of a sword with its effectiveness, especially against unarmored foes — and nobody is wearing all that heavy and expensive armor when they're about their business. Maces, warhammers, and similar weapons are very effective against armor, but decidedly inferior to a blade versus an unarmored foe, nor are they as convenient to walk around with. Axes meant for combat are not the same as tool axes; a tool axe is relatively easy to carry, but one made for war is encumbersomenote . Polearms and spears are a pain in the posterior to carry about and sure to attract attention. Everyone has a knife (so they can cut meat, if nothing else), and a sword is a much better weapon. The sword would be the natural choice to wear if you could get away with it.
Swords also required a greater deal of training to use than most other weapons, with various advanced techniques, parrying, and wrist motions, which marked swords, and the people who used them, as an elite few relative to the "Common" axe-swinging rabble.note
There is a clear parallel with our times. A modern soldier on a battlefield uses a rifle, as it is a superior weapon. A modern person who wants to be armed day-to-day carries a hand gun, as an AK-47 is very inconvenient to carry at all times and will get you in trouble. A medieval soldier on a battlefield typically uses some variety of polearm, axe, or hammer. A medieval person who wants to be armed day-to-day carries a sword.
