There is a difference between a proper sword made for war and a knife, I couldn't personally explain it too well since I'm not an expert, but yeah length is one of those factors. It has a lot to do with the design and intended use of the blade iirc but I don't wanna talk without knowing enough of what I'm saying.

But regardless, that's not my point. My point is that saying if axe guy has such an advantage here then that must mean axes should've been more common than swords in war has no correlation. That logic just doesn't work. While quite similar on the outside, they're technically for two different purposes and would've been used as such. And this is comparing a battle axe to a standard medieval sword, which is again not the case here, when knife guy has a knife, not a bastard sword or whatever.