I agree wif (most of) da op.

I have no problem with accuracy, but Determination as mastery would go a long way towards making stats more interesting. Some of the specific effects I would change, though.

Specifically for paladin: Reduced cooldown on Sheltron, Shield Swipe, and Circle of Scorn
ninja: hard to say, but Huton duration isn't amazing. Maybe reduced CD on Ninjutsu or, if that's too strong, increased duration on Trick Attack.
dark knight: chance to proc free Dark Arts

Parry could reduce defensive ability cooldowns or just give straight phys/magic defense.

It'd also be nice if our "bonus attributes" were put into secondary stats instead of primary stats. They're kind of stupid right now.