I would really like to see dark knight gain an extra mechanic bringing its kit together. I would love to see blood usuage lower the cooldowns on BW and/or C&S and have mana consumption lower the cooldown on delirium. It would add a layer of complexity to the job since it does feel a bit simplistic now.

I think the OP hits the nail on the head with many things, especially shadow wall.

I would add giving an extra second to TBN to make it two server ticks, an add free use of sole survivor, interplay between blood and mana, a dps buff, and more mp regeneration are the necessary changes which need to happen before raid.