1) We identify the core aspects of the job in lore and what it stands for, which will bring draw to those who do the DRK job quests. In this instance, Living Dead rework is what everyone has called for time and again. An idea I thought of was changing Living Dead to Shadows Die Twice, which would on a fatal blow restore all your HP and inflict you with Walking Dead - to prevent your HP from falling to 0 after the HP Restoration for 8s. I got the idea from someone in the DRK Megathread that mentioned 'Reverse Superbolide'.
However, the consideration of Dark Arts from back in Stormblood was something that is not entirely missed due to the 'treadmill' effect that people so hate.
So, I suggest we turn Dark Arts into an individual 30s CD that augments Souleater to become Power Slash(Sub 90)/Shadowbringer(90), forgoing Blood for higher raw damage equivalent to Blood Gain and granting Dark Requiem at 90 - recovering MP over time at a set rate. The worry of too much MP is heavily mitigated by the fact they've already simplified DRK's MP usage, which is mostly used on Edge/Flood/TBN. Adding a second combo is also a priority considering DRK is akin to how PLD was in simplicity in ARR currently - so adding a Blood Combo as you suggested in one of the later pages of this thread would be favorable. This would keep Souleater as your sustain combo, which generates 20 Blood per use, while this second combo would instead inflict a debuff on the target that grants DRK 10 Blood per GCD while it is up.
Scourge would make a return, considering the fact that we've always thought of "powerful" animations, and not a single DRK that played the job in HW forgets Scourge. It'd be a Single Target CD DoT akin to Sonic Break, but would be on GCD - it also would not break combo, giving DRK some needed breathing room when weaving oGCDs compared to now.
It would also make sense to replace Oblation with Sole Survivor, a buff that if your HP is <=50% Max HP, you would recover a set potency. This would lean towards DRK's lack of sustain that it desperately needs outside of Souleater HP Sustain buffs.
Changing Dark Mind from Magic Mitigation into a 10% would make things far better for low level as well, as learning it doesn't do much due to the heavy lack of magic damage in a majority of content that this ability is supposed to be used in.
Blood Weapon getting the Requiescat treatment it desperately deserves to have. 5 stacks, 5 GCDs of MP.
Keep Delirium, but instead of it being the same 'Unga Bunga' button that WAR is used to, have it grant a buff that for every 3000 MP you have, convert it to a stack of Premonition that can stack up to 3 and does not have a timer associated with it. It can only be used during battle so as to not cause any pre-pull issues. To prevent conflict with TBN, TBN should simply be a shield with no MP Cost, no Edge/Flood tied to breaking so the ability doesn't become convoluted into "I need to break it to get more DPS" like it has been since Stormblood.
2) The job's leveling scheme needs shaping up, since at low level it feels horrible to play, even all the way to max level, due to one less defensive caused by Dark Mind, which is useless in 90% of content. Moving some abilities such as Stalwart Soul down to the 40 baseline like other tanks would bring it more in-line with what is expected in a new-player experience, and would make it feel less like a drag outside of the story gameplay wise. At 72, it'd have the trait where it would grant Blood upon combo.
3) By distinct, it needs to attain an identity. The only identity I remember that made it stand out in Heavensward was the fact that it had this focus on MP Management - something we should bring back in some shape or form that would fit the bill rather than just slap "Just use Edge/Flood/TBN" considering I chose to bring Dark Arts as a Finisher augment.
There's probably more that can be done to make the job distinct, but this is all I can think of right now in terms of what may make the job actually 'feel' better in terms of flow.