DRK also brings better CC than WAR. Brutal Swing + Holmgang is very good at locking down an important target, yes but DRKs can prevent an entire party from running away. They also have a blind, but it's not as spammable as PLDs.
Also I would argue that DRK does better damage outside of their burst, too. If a WAR doesn't have Berserk, they have to prep maim every time they engage someone, build up to 5 stacks of Deliverance, (Or infuriate) to Fell Cleave. DRK requires no prep, and can instantly use it's highest damage combo at no loss.
WAR definitely wins in the self preservation department though, and they're a better job to 1v1 with by far.
Edit: Whoops, forgot WAR has Mythril Tempest too. So their CC is pretty close, but still not as good as PLD.