Vengeance vs Sentinel was fine in ARR. 40% 180s vs 30% 120s. Shadow Wall is bad (like a lot of DRK's skillset) because it's just a copy of something PLD has but slightly different (no trait).
The 3 invincibility cooldowns are pretty balanced. Holmgang is up the most often, but it has the shortest duration, requires a target, roots you, and either requires you to pop 2+ cooldowns and tank stance to get a decent amount of HP back, or a healer just like Living Dead.
Butcher's Block+Storm's Path damage? WAR loses DPS to apply its mitigation, PLD+DRK lose damage to generate more enmity. Path's healing is completely irrelevant outside of soloing level 50 content, it barely equals a Regen tick in Deliverance with a crit or Berserk. I don't really see a problem there.
Path mitigation? PLD has Halone and Divine Veil, which is actually really strong. It's currently a 2.8k shield on the group. DRK has Delirium and Reprisal, which copies Path's debuff and doesn't cost DPS to use.
Equilibrium? Why do PLD and DRK have skills that are completely useless for half (or more) of a fight? It's not WAR's fault that PLD has skill slots wasted on trash like Cover or Tempered Will, or that both of them have procs that requires them to get hit, or that DRK has so many slots wasted on skills that are purely for DPS. Why do they have Dark Arts if it's going to affect almost no skills?
Defiance/Deliverance and their skills? PLD gets access to all their skills in either stance, DRK loses Blood Weapon (which is stupid) and Souleater's heal. WAR loses its main mitigation skill and a big part of its DPS rotation depending on stance.
In the end, the problem is that SE made DRK too similar to PLD so you never want to have them in the same group. There's so many ways they could be made unique so that any tank composition could work, but all people can focus on is that WAR actually does stuff different to the other two.