DRK does not need to be the lifesteal tank. That role should go to WAR, mostly to make up for their lack of mitigation on their tank stance. It fits a berserker archetype better regardless, which is what WAR is. Bloodbath originally belonged to them for a reason.

DRK's role should be focused more on debuffing their enemies as opposed to supporting their allies, at least in terms of utility. That is more in line with their gameplay across the series as a whole as well. Some of their mitigation can lean towards magic, sure, but that's part of their problem at the moment. Maybe the best idea is to simply accept that self mitigation is self mitigation, regardless of whatever damage type is being used. To that end, Dark Mind should either become universal with a longer cooldown on DRK only, or join the role action list for tanks. Either or works, but if the latter did happen I'd expect Reprisal to go back to DRK, or for DRK to get a stronger version of it as an exclusive ability.