I've recently started getting my DRK from 60-70, after leveling my PLD and WAR to 70.

All I can say is I take a ton more damage, and have less CD's for mitigation. If Dark Arts > Dark Passenger (Blind) is meant as mitigation, it costs WAY too much mana to apply it. Perhaps put some mitigation on Blood Price.

Basically, I just FEEL gimped as a tank playing dark. Can't really describe it, I just feel weak. Especially if I get synced. The unleash nerf sucks bad.