I agree DRK (and PLD) need changes, but the OP suggestions would suck all the fun out of DRK.
I'd prefer changes that make it easier for DRK to be more independent from the healer (looking at you living dead) and make it easier to spend more time out of grit.
Blood weapon: changed to a stance that cannot be active at the same time as grit. But half the effect (reduced MP return, 5% haste, 10% tp cost reduction). Because this would stop all the "let us use it in grit" whining as people would get that it's a dps stance not a cooldown.
Shadowskin: add dark arts effect to increase enmity while active (turning it into a short time grit). Because DRK and PLD need more enmity, WAR just trounces both of them in and out of tank stance on this front.
Shadow wall: add dark arts effect to add a 50 potency counterattack. Because as it is right now it's just a gimped sentinel. Vengeance has a counterattack and shorter cooldown, sentinel reduces 10% more damage.
Souleater and abyssal drain: drain 50% of damage dealt as hp (without grit/dark arts). Soul devourer trait changed to increases absorb to 100% while in grit. Abyssal drain dark arts effect changed to absorb 100%. Because it drives me nuts that these clearly drain based skills don't drain without special circumstances!! And DRK has a lack of self healing compared to the other tanks out of tank stance.
Plunge: add a small knockback, just enough to interrupt an enemy cast (similar to holmgang). Because DRK lacks interrupt capabilities compared to the other tanks having only 1 stun and nothing else.
Walking dead: adds 100% absorb hp to all attacks, stacks with bloodbath and souleater/abyssal drain. Because living dead sucks when you have to rely on your healer and can't use it for its anti-death purpose without one.