Despite the majority, I have overall been enjoying Dark Knight in DT. My experiences in Dungeons, Trials and Raids as Dark Knight have been overall positive. This is anecdotal and I know it is not the experience of many players.
While Dark Knight shone DPS wise in Abyssos, that is currently not the case and Dark Knight's issues go far beyond its damage, which should be addressed either way. While I do not know how the overall job should be reworked, I do have ideas that I believe could relieve some of the issues Dark Knight has in terms of survivability and clunkiness of certain actions. I didn't play during HW or SB so I can't speak on which if any actions should return.
Changes to Mitigation
1. Dark Missionary unlocked pre level 70
2. The Blackest Night updated: Function similarly to: Arcane Crest: Upon breakage, The Blackest Night grants a low potency cure that lasts 10-15s, Tempera Coat: Upon breakage, The Blackest Night recast timer is halved. If The Blackest Night shield breaks, player is granted 5-10% mitigation for remaining time
3. Shadowed Vigil updated: Allow players to activate HP restoration at any time or any HP value, Shadowed Vigil gradually restores HP during the duration of effect
4. Dark Mind Updated: Reduce Magic Damage mitigated by 5% add 5 or 10% Physical Damage Mitigation
Changes to Combat Skills
1. Unbind Abyssal Drain and Carve and Spit recast timer: Reduce Abyssal Drain recast timer to 30s
2. Salted Earth/Salt and Darkness updated: While standing in Salted Earth, the player gains 5% damage reduction, Abilities and Weaponskills used while standing in Salted Earth heal player, Salt and Darkness activation grants HP equivalent of enemy damage done to player
3. Delirium updated, Delirium remains 3 stacks, Blood Weapon stacks returned to 5 stacks
4. Living Shadow/Esteem Updated, Reduce spawn time of Esteem, Esteem uses updated Delirium actions, Damage done by Esteem’s Abyssal Drain is granted to player
5. Make Unleash and Stalwart Soul affected by Skill Speed
Now to my history in this game for those that care
Began playing in 5.1
My first level cap tank was GNB, but eventually leveled and played all tanks
Began tanking out of desperation when Diamond Weapon/EX was released
Started tanking seriously on WAR and DRK (found it very hard to tank in EX Trials on GNB and PLD)
Cleared all HW-ShB EXs on WAR or DRK
Cleared all EW EXs on various jobs, more recently cleared Zeromus EX on content on PLD
Cleared DT EX1 on DRK
Cleared most of Abyssos Savage (P5S-P8S P1) on WAR or DRK