How is this fair for DRK?

[Crater]

You are a fool if you think they're nerfs. Dark Mind is straight up useless against anything physical

I suggest you take a look at the distribution of damage types across tank-threatening enemy attacks in the current selection of high-end content (or the selection of high-end content from the previous expansion, even). This is not the trump card argument you think it is.

Dark Knight currently has the ability, through Dark Mind and Oblation, to throw 28% in combined percentage-based mitigation at almost every instance of relevant tank damage in the game, on a 60-second cooldown, without even touching Rampart, its 30%/10s/120s cooldown, or its short-mitigation.

You're asking for that to be reduced to 15% - and you don't think you're asking for a huge nerf to the class.

And for... What, exactly? Dungeon performance? Get real.

Re: "TBN can't compete with the others", getting into detail on that a post and a half. Suffice to say, I don't agree; there are four basic use-cases for short mitigation skills (against Low, Threatening, Lethal, and Sustained damage) and the one everybody seems to be fixated on TBN being bad for - Low incoming damage, like dungeon bosses - is almost completely irrelevant. In every other case, TBN acquits itself just fine - largely due to its low cooldown, which you are campaigning to have nerfed.

If Oblation is irrelevant, then why isn't it being changed?

Shake it Off was deemed to be irrelevant at the start of Stormblood. The dev team tripped over themselves to put a rework out to quell the WAR playerbase.

You won't catch me defending any of the travesties of tank design and balance that SE committed during Stormblood, but two things here: A) They weren't exactly tripping over themselves to change Shake at launch; that didn't come about until 4.1. The panic changes for 4.05 were just to get rid of the gauge consumption on stance-swapping, give a self-heal to Steel Cyclone, and eliminate gauge costs for Unchained/Inner Release. And B) My own misgivings about what happened with Shake it Off aside, the complaints there weren't "This skill is a too-weak version of what we want it to be" but rather "This skill does something that we view as useless". The basic functionality of Oblation isn't a problem at all; people just want it to do the same job a little bit harder than it does right now.

Also, I admit this is a little pedantic, but: I didn't say it wasn't relevant. I said it didn't feel relevant. When the only content to use it on is two overgeared Extremes and a Normal mode raid, Rampart barely feels relevant. I expect its value will become more apparent in Savage (and I expect that value to be small enough that I'll still think it needs a small buff).