Personally I don't see why so many ppl complain that it doesn't make sense "In real life" that 2hand weapon has more accuracy, I mean this is final fantasy and characters use magic, armor and avaters. SE are trying to make the game balanced by allowing two hand weapon users to equip attack stuff to further enhance their damage instead of having to worry about accuracy.
I mean, if you want to compare to real life, then in reality a GS should be able to chop off someone's arm or leg everytime it connects, which you should never get hurt by something like a one hand sword if you have armor on. So let's say 2hand weapon should kill a dragon in 5 hits, two arms, two legs, and then head, while one hand weapon shouldn't even cut open a dragon's skin. Yet I dont see two hand weapon base damage is 10 times better than one hand weapon in this game. So in order to make up with the non sense, SE decided to give more non sense that two hand weapons give more accuracy.
At least it makes the game balanced. Don't tell me it is not real. Nothing is real in this game period.
Except that you're not accounting for precision, or type of weapon.
A 1h Axe would still have a lot of chopping power, which obviously something like a Rapier wouldn't. But that Rapier could be slipped in between plates of armor to do damage, whereas you'd have a hard time doing that with an axe. You'd need little room to manipulate a dagger so slit someone's throat. Could do it from close enough that they wouldn't be able to effectively hit you with a staff.
While a Greatsword should be able to lop a limb off, an archer should be able to put a bolt through someone's heart or through their eye to the brain to one-shot 'em.
While nothing is "real" per se, that doesn't necessarily mean that reality couldn't be used as a reference point when determining how to build a set of rules for combat in a game. Since weapons have classes based on real weapon types, why would it be a stretch to base their properties on those of real weapons?
Single wielded weapons swing faster, they should have a higher rate of parry, be more accurate, and get higher damage criticals compared to their base damage. Two handed weapons should hurt, but it makes more sense that they'd take longer to swing, miss more, and be harder to block with.
Along with that though, dual wielding weapons would make things less coordinated too.