Shield barrier is OP compared to other tanks. DK Blood Shield doesn't absorb magic, you can't dodge spells with Savage Defense as Bear nor can you Block them as a Paladin.
What, wa.waht!?
It absorbs a lot of damage, sure. But compare a shield barrier slamming warr to a self-healing paladin/DK on ANY fight and you will see who wins out.
Absorb > Heal, Heal is often wasted since you have healers over healing like a bitch.
Absorb is never wasted, unless you don't take enough damage before the buff to runs out.
You pretty much nailed it right there, and that is why i prefer warrior over for example dks, however dks are really epic to solo stuff with, warriors cant depend on second wind heh