That's because DRK came in HW, but I personally still wouldn't make it a lifesteal tank. Simply because that was never in DRK's identity in FF. It did usually have a drain spell in its dark magic spell list but that's about it.

DRK needs to be a magic shield tank, TBN is what it's known for so it should expand on that, like a personal Haima. Change Darkmind into something that absorbs blood with every GCD into its shield and for HP Abyssal Drain should be a spell with cast time, single target 800P heal with splash damage+healing. Finally, Souleater gives a 200P shield and 200P heal.