A simple Dark Knight change that I think would massively help the job

[Althanash]

Honestly as someone who's played DRK / GnB / Warr. I've only really found DRK to lack when it comes to self healing out of the 3. It performs pretty well otherwise.

[Selvokaz]

needs some selfish HP stealing, basically put Bloodsucker on all its melee attacks and MP Drain on the 2nd one like it already has, and make Abyssal Drain a spell again that can be chained into the 3rd hit of the AOE Combo with increased potency and you're good.