I actually wouldn't mind cover being moved to a role action. in its current form, it is very costly in terms of oath gauge, with a lengthy cooldown to boot, and it sometimes doesn't get used by PLD due to the distance from the person they're trying to cover unless the PLD is offtank.

there have also been plenty of times that I would wish I could give some form of mitigation to others when playing DRK below lv 70, and this would be a really solid way of giving all tanks a way to mitigate team damage while not being so strong that it can be abused. maybe its cooldown would have to be lengthened to accommodate for two tanks being able to use it in the same instance for trials. perhaps 180 sec cd?

as for the hole left in PLDs kit, i'm not too sure what could be added. I wouldn't want to see another defencive cooldown, as i believe changing sheltron to a base 8 second duration at lv 35, and giving it a trait to decrease its cost to 30 gauge at level 66 or so would be much better for its kit, but i guess replacing cover with another defencive cd would ease that issue. maybe bring bulwark back?