The Warrior/Knight classes are only OP in the sense that they've got about 3 or so interrupts. As far as damage, they seem pretty balanced. I mean the entire job of a Warrior/Knight is to dish out damage and lots of it. If you're having issues dueling them, learn some strategy. I rarely lose to a Warrior/Knight anymore mainly because I acknowledge that they're only good if they're in your face. Get some distance, move around, use cool-downs, etc. The best way to beat them is to practice fighting against them. It's pretty common knowledge that once Undying Rage is activated, you can't hurt them for a period of time so that's when you get defensive. As for me, i'm an assassin so I cloak out and wait. Then I spike, assassinate and mourn.