You can make an attack of opportunity against someone in your reach who is casting a spell. Sounds good. Except that in the action system combined with AoO being locked to only one class the spell caster will just move away before casting their spell.
Then I thought it would synergize well with No Escape, but that uses up your reaction, so you can follow the wizard and then ... stand there and do nothing while they cast a spell in your face.
To top that off you can only use it while raging. How are you even going to get to use it? How often are spell casters going to be dumb enough to cast a spell while standing next to a guy with a big weapon.