This... does not sound very Defender-y. Really, it's more like a Controller/Striker - single target debuff with lots of damage powers.

I mean, look at the basic description:
Quote Originally Posted by PHB 15
Defenders have the highest defenses in the game and good close-up offense. They are the party’s front-line combatants; wherever they’re standing, that’s where the action is. Defenders have abilities and powers that make it difficult for enemies to move past them or to ignore them in battle.
Yeah. What we need is a Defender to keep the Barbarian from being focused-fired while she Rages. It may be a very good class, but I still don't see how it can be called a good Defender.