The fact that Quietus restores MP drastically helps. Curiously, it did not restore MP upon Stormblood's release, this was patched in later. With Blood Price's major nerf, it made wonder if they intended for it to restore MP and forgot to add that as an effect, or added it in later after realizing Dark Knight's underperformance. I was always deeply unsettled by this seemingly emergency fix, it could have possibly been an afterthought that just did not occur to them during Dark Knight's Stormblood development, which says a lot...but I digress.

That aside, I think Dark Knights and Quietus go well together now, as it creates one of the most fun tactics in the game for me, certainly the most fun of any class's AoE: Blood Weapon + Quietus. This fast paced little dance is one of the main reasons I've stuck with Dark Knight through Stormblood, as it's some of the most hectic and cool things I've done in the game. The relationship between Salted Earth, Blood Weapon, Quietus, Dark Passenger and TBN allows for the potential to top the DPS charts and reduce or even completely replace healing from your healer.

It may not compare to a fully Inner Released Decimate spam, but I don't think it's supposed to. The way Quietus works for Dark Knight's AoE game now allows for cool potential that I wish was more prevalent in their single target playstyle.