2H damage is only broken because of the Axe Zaleskar sells. It's too powerful. Name me one situation where you don't get it. The stats are insane.
The skills do need a nerf across the board, that I agree with. 20% would probably be enough of a nerf to leave them viable, but not game-breaking.
Actually you don't need Sundering Cleaver to dish out unbelievable amounts of damage; I managed to score a critical hit worth 140 points with just a 2h mace with damage in the range of 56-62, or something like that, just by using rage and then cripple at level 4. It's the system in itself that is OP, not just Zaleskar's axe (although that thing does certainly help in rekking anything that stands in your way)