If the Warrior is the heal tank, Then why not make The Dark Knight the shield tank?

Here's my idea.
Flood and edge of darkness now give a shield based off of damage dealt. 30% for edge and 5% for flood. (Yes 5% per enemy hit). You loose the damage buff, but every thing else stays the same.
TBN now is on a 25 sec cooldown. It still has the shield but when it wears off it gives you a minor heal. If the shield breaks you get double the heal and it is a critical.
Blood weapon is now the standard damage buff that all tanks get.
Abyssel drain and sacred soil merge into one. Now it is a aoe dot and hot. The hot also works on any party member. It is also on It's own ogcd.
Your 123 combo is different. 1000 mp on your 3. And your 2 gives more blood gage. (1000 mp because you loose blood weapon mp generation)

That's all I could think of right now. But I hope that I expressed my thoughts clearly.