I honestly don't think there's any need to "give up on" HP-sacrificing skills/mechanics, especially if DRK also has access to lifesteal effects (and all the more so if they're very on demand, such as through a bankable Blood Weapon or whatnot). Complement the HP-sacrifice mechanic with even just, say, a single auto-save mechanic, like Living Dead activating automatically if you're struck by fatal damage (with 5+ minutes before that effect is available again), allowing you to essentially fall into negative HP for up to 10s and finally putting that long-requested 3D timer above your head, and I don't think healers would be jumping out of their skin over DRK being able to sacrifice HP.
Again, I just can't think of that as any more sensible than "only one healer should ever have shields/HoTs/on-ally buffs".I say that, because Ninninin aside, I have seen other Dark Knights that are mad about Warrior has convert-damage-into-HP self-heal effects, more than what Dark Knight does, and I have no idea how many Dark Knights feel that way... while.. say that both Subclasses, Dark Knight and Warrior, have the convert-damage-into-HP self-heal effect... Then come the complaints about the two being too similar, in another way than they already are, so either the complaints are ignored, which at this point is what I think may be better, or the complaints are addressed and one Subclass loses the effect in question.
I have to be the villain for one of the sides, when it comes to the decision of which Tank takes the loss, in which I chose to be the Villain for Warrior, as a personal opinion.
For WAR, it's actually more written into the flavor text / theme than for DRK. It's literally... the thrill of combat invigorating them. The more they can do, the more they can sustain themselves.that aside, my opinion is that Dark knight and Warrior should both have convert-damage-into-HP self-heal effects, and although I have no idea how to explain that for Warrior, where-as with Dark Knight I can just call it Blood Magic.
On that note, though, there's also little to no magic sword of vampirism/blood magic hoodoo in DRK's questlines. It's more about the psychology of it all, somewhat mirroring but still quite distinct from WAR's.
Doesn't take much pretending, given its iterations as listed before came out in 2008 and 2012, and are a mere extension of Cecil's character itself, whereas XIV's came out in 2015.