DRK feels weak

[Luin]

Being good in a small niche is great and all...but what about the other like 80% of the content in FFXIV? xD

The battle system is balanced around full party content and always has been.

Outside of the role actions, WAR has Vengeance, Bloodwhetting, and Shake it Off

You forgot Thrill (effectively 20% mitigation). Most Endwalker double pulls are easily handled with just Thrill+Shake+Equil and 1 or 2 Bloodwhetting casts. WAR has the most defensives.

people don't realize WARs are taking huge spike damage.

What? They have Holmgang - an objectively superior invuln to Living Dead.

Like say WAR has Vengeance+Whet, and WAR has Corundum from cotank, that's 59% mitigation. Add Thrill, 20% increase in max HP, that's almost a TBN itself (plus 400p shield from Whet). How is that spike damage compared to any other tank?

Compare to DRK. Let's say ShadowWall+TBN+Oblation+Corundum. This is 54% mitigation, plus 25% shield. Yes, TBN is the most potent mitigation for singlehit busters, but busters are not balanced around TBN. They're survivable with any tank comp.