RE Parrying with the edge vs the flat, if I may throw in a few points? First, practical experience with HEMA, in which I've personally always been taught to parry with the edge (except in smallsword, since it doesn't really have one).
Second, damage to the edge of your sword while parrying isn't really a big issue; parrying is usually done with the forte, the half of the sword closest to the hilt, whereas attacks are made with the foible, the upper portion closest to the tip. Damage to the edge at the forte, then, doesn't make much different since you don't cut with that portion of the edge.
Third, there's a good chance that parrying with your own flat is more likely to cause your blade to bend or even snap. It's easier to bend a blade when applying pressure to the flat, since it's thinner.
RE Parrying with the edge vs the flat, if I may throw in a few points? First, practical experience with HEMA, in which I've personally always been taught to parry with the edge (except in smallsword, since it doesn't really have one).
Second, damage to the edge of your sword while parrying isn't really a big issue; parrying is usually done with the forte, the half of the sword closest to the hilt, whereas attacks are made with the foible, the upper portion closest to the tip. Damage to the edge at the forte, then, doesn't make much different since you don't cut with that portion of the edge.
Third, there's a good chance that parrying with your own flat is more likely to cause your blade to bend or even snap. It's easier to bend a blade when applying pressure to the flat, since it's thinner.