The thing is Jack if DRK has a solid kit with key holes punched in it and also leaves a lot to be desired then that in itself attributes it to poor design.

What they need to do if they want to push it as the bonafide magic tank it needs abilities that absorb Magic Damage, block magic damage, give additional ways to use Dark Arts such as forcing reprisal when offtank(relying on a parry proc means MT or go home and Parry is ass anyway), forcing blood weapon in grit to give HP instead of MP, give them an on demand provoke through DA Power Slash and hell swap out Int Down on Delirium for Magic Vulnerability up. And something needs to be done with Living Dead. Period.

You cannot design an ultimate defensive skill completely around the raid environment and assume the DRK and it's healer have a vocal channel open all the time. You sacrifice all for nothing with the skill and get no buff out of it(which why our stats aren't getting buffed by at least 20% during LD/WD is beyond me) except for what so you can die slightly later? Meanwhile the PLD/WAR over there can definitely make a comeback with Clemency and a plethora of Self heals? I mean if Convalescence buffed Souleater I would complain much much less.

Will it fix mah beef with no HP cost skills for the deeps? No. But it would make the class have a form of identity and great utility. Which would be the magic tank of the game. And right now in the long run it will struggle and only be taken if 80% of a fight is magic damage for just manageable mitigation. Otherwise it's take a PLD if Physical or play it safe and go WAR.