I play as a Knight Enchanter, and I'm finding it very fun, but not OP. I get hit, (sometimes, lol) I take damage, I've even been KO'd.
It's strong, but doesn't feel broken.
Blackwall on the other hand..... Lol
While fighting my first dragon, HE was the only one who didn't need to use a potion to heal. In fact, he took zero damage by the time the battle was done. Not that I'm complaining! 
At higher levels, and it IS needing to be said - only if you spec right, KE an be truly dangerous.
If you spec it in a normalized way, it's more or less another mage class. Simply with the ability to smack SOBs with a giant blade of light.
I'm not trying to DEMONIZE KE's now, if that's how my previous post came off I apologize. I just, as with the OP from the sounds of it, recognize the ability to truly cake-walk through the game.
I suppose this is obviously a players choice, I guess maybe I'm just wondering why it was enabled to have this effect? If I spec out a Reaver in a specific way - does he or she become the same way?
Can I spec out a Champion, as to your credit, and become a immortal?
Perhaps it is not ONLY the KE that has this "Broken" standardized situation - but it IS the most OBVIOUS one I have seen. Personally, anyway.