I have mostly final version of my own personal wishlist for Dark Knight rework, with an attempt made at compromising at what some other people would want. It is meant to be read and responded to in one go, and if you don't understand it the first time, take the time to read it as many times as you need to fully understand it, ESPECIALLY the Dark Arts section, and MAYBE the Darkside section as well.
(Slight rework + Quality of Life) Make Salt and Darkness into GCD spell that combos after Stalwart Soul and move it to level that Salted Earth is and it would make AoE feel slightly better, though could make Stalwart Soul and Salt and Darkness restore MP, Blood gauge, and restore HP equal to damage dealt per hit(see the Melee DPS Role Action Bloodbath for more details). Would also need to apply these affects to Unleash, Stalwart Soul, Hard Slash, Syphon Strike, and Souleater. For those who still want the lingering DoT field, Salt and Darkness can apply Salted Earth as a combo bonus.
(Major Rework + Quality of Life) Make Blood Weapon be a mini Darkside that grants 15-25% haste(would probably need to make this effect universal for all tanks in some way) which then becomes Darkside when you do the quest to unlock it, and then have Darkside upgrade into Delirium to where it generates a Dark Arts stack every 15 seconds indicated by the Darkside timer(or gauge as the devs called it) and have Delirium become Living Shadow A.K.A. True Darkside with the dark flames aura that also boosts potency by 100-300(would also need to make universal for all tanks in some way because Tank Mastery Trait is just THAT BAD), and we can keep the ways to maintain Darkside and have those apply to Blood Weapon and Living Shadow. Basically I just want to turn and maintain Darkside in and out of of combat with the haste effect of Heavensward/Stormblood Blood Weapon. For those who still want the summon pet mechanic, add a new ability called Summon Shadow and its duration and AI needs to be more like a Trust/Duty Support NPC that does Tank mechanics, give it an AoE Rescue for specific group mechanics, but CANNOT be used while at the same time as Living Shadow and should Esteem be KO'd, it grants Living Shadow automatically, or just keep as is right now which is basically a summon pet for 20+ seconds takes forever to wake up, and is not affected by Darkside bonuses.
(Major rework + Quality of Life) Bring back Dark Passenger, make it GCD that costs MP, and have it combo into Flood of Darkness/Shadow, which then combos into Shadowbringer, and they all cost 3000 MP each, because the MP guzzling aspect of Dark Knight is enough to make it stand out from the other tanks, I just wish the MP spenders were GCDs, and I wish they gave Blood gauge, and restored HP equal to damage dealt per hit (see the Melee DPS Role Action Bloodbath for more details) and were DPS neutral in single target to Blood gauge spender at the start and ramps up, and you could make these share 1 button space like Gnashing Fang combo or Confiteor combo. Could also add a predecessor to Shadowbringer at level 62 with 80 less potency than Shadowbringer. Make Edge of Darkness/Shadow become a GCD weaponskill that cost 20 Blood gauge, that combos into Bloodspiller that costs 15 Blood Gauge, that combos into Carve and Spit that also cost 15 Blood gauge, and they could restore MP and restore HP equal to damage dealt(see the Melee DPS Role Action Bloodbath for more details), and you could also make these share 1 button. Make Quietus cost 15 Blood gauge and have restore MP, and boost its potency, and make Abyssal Drain a GCD that cost 3000 MP that restore Blood gauge, make both restore HP equal to damage dealt per hit(see the Melee DPS role action Bloodbath for more details) and boost its potency, and people would would try to find a use for these. Could also keep Abyssal Drain an oGCD with 2 charges on 30 second recast timer. Dark Arts button we can bring back as 60 second cooldown which grants 3 Dark Arts charges, which double the potency of all actions, ignore resources for 3 actions and if used on Dark Passenger, Flood of Darkness/Shadow, and/or Shadowbringer it converts Dark Arts into a new resource called Blood Arts which is basically triples damage dealt for Blood gauge spenders, but only in combat. The Blackest Night have the MP cost removed, but would need it's recast timer increased to 25 seconds, and if falls off 1 Dark Arts charge, if it breaks it grants 3 instead. Could also have Dark Arts reduce recast timers of MP spenders to 1.5 seconds. Additionally could also make Souleater and Salt and Darkness generate a Dark Arts stack if you have ONLY 2 stacks of Dark Arts.
(Something new) Bring back 4.3 Sole Survivor, buff it to where it increase damage dealt to enemies by 5%(or damage enemies receive to better understand it) and reduce the amount of damage that those enemies would deal to players by 10%, have it be 2 charges, and it would give Dark Knight a raid buff that's good against bosses and also good in dungeons. Not good for when bosses become non-targetable to keep it balanced. Could also have it deal damage and make the recast timer 30 seconds but the duration is 10-ish seconds.
(Quality of Life) Have Dark Mind get the Addle treatment, and it would feel less bad against physical tank busters. Also give Dark Missionary the Addle treatment on the off chance there is physical raidwide, and by extension Heart of Light since the effect is copy-pasted on Gunbreaker already.
(Slight rework + Quality of Life) Just make Living Dead just be a 20 second invuln that drops your HP to 1(you still take damage) that restores HP equal to damage dealt by 300%, and it would be a better than Holmgang, and justify the 300 second cooldown. Yes I am aware that the other tanks would complain about their invuln not being as long as Living Dead but that's the point, since we all know that the devs would give the other tanks a 20 second duration on their invuln as well..
All of this would make up for the fact that Dark Knight would no longer have a massive oGCD spam during the course of fights, and feel (and look) a lot less janky to play and would probably make Dark Knight be SO MUCH better than when it first launched in Heavensward, with a lot more opportunities to pop a defensive or utility during burst... This would also address the button bloat issue, as well as introducing older abilities to people who did not play Heavensward when it was relevant, while still introducing new abilities, for both earlier in Dark Knight leveling and the obvious new abilities the we might be getting in the next expansion, and make leveling Dark Knight from 50-60 feel less braindead to an extent, because spamming 1-2-3 for more than 10 minutes might cause some kind of brain rot...