In my opinion, 2H is by far the strongest solo-melee-class.
For teamwork, i would rather have a shielder who cna take hits or someone with a long polearm, but for soloing people (such as leshima) 2h is very strong with good damage, good speed and, and this is by far the best about 2H, superior animations.
the 2h animations simply make them so much better in 1 vs. 1, which, in my opinion, is enoguh of a balance.
i recently respecced to 2H, and i experience that every aspect is much easier compared to the polearm i used before (except supporting where i had my long spear)
it's no coincidence that most of the top duellers are 2H.