Clue 1: There is a reason you don't see dark knights in speed kills using TBN every 15 seconds. If it was DPS neutral people would absolutely be looking to maximize this skill usage in order to maximize healer damage. Once again, TBN is powerful mitigation, but it isn't as strong as paladin's kit against reasonably spaced tank busters, and it isn't as powerful as warrior's kit which covers both busters and fluff damage. Dark Knight mitigation shines more in god kefka where there are frequent magical tank busters, but progging with warrior/paladin comp the advantages offered seem really overblown.
Clue 2: The fact that warriors are getting away with only using a subset of their kit doesn't point to the kit being weak.
How are dark knights self-healing themselves? Are we talking about the undesirable grit locked soul eater that warrior has access to in both stances? Are we talking about Sole Survivor that can only be used on adds once every 2 minutes if the raid just happens to include them (thankfully more did include adds this tier)? Or are we just talking about plain old abyssal drain which does little inside a raid?
Warrior's might give up a chunk of dps when trying to do something similar, but hey, if you are healing yourself its usually a "do or wipe" situation, and in that context warrior does it better and more effectively than anything dark knight can do. Same can be said for paladin, if the chips are down, spam clemency and pray will get your further than grit and soul eater.
I agree, the only thing I would want to see changed about dark knight mitigation kit is a physical analog to dark mind for leveling purposes and to make the dark knight mitigation more well rounded.
Overall I think the lacking dps is the bigger issue the class faces.
