[Trexmaster]

I want to say it's because of the way Wraithguard works versus every other DR in the game.

Wraithguard takes from a pool of HP the Wraithguard mob has to grant the DR in question, effectively acting like a damage shield, no other DR outside actual damage shields (literally just Jarmor I'm pretty sure) act like that.

The only oddity is when the Wraithguard runs out of HP to block, though in a way its functionality is the same as the whole one damage shield we have. It'll apply its full reduction to the last damage instance that it applied to even if it'd run all of its remaining resources down.

I think this would be best served as a Balance Fu post if you wanted to suggest Wraithguard no longer apply to DR-ignoring abilities.