I'm not exactly a fan of ShB DRK, but I do agree that a good foundation is needed. It's just that SE went with the simplest and safest foundation they could, making it overall pretty boring while the other jobs have a "nice house" already build upon theirs.
I definitely do agree that they should buff the duration of TBN, 7 sec is simply not enough to be broken with auto attacks in savage raids - especially with the buff to 25% HP now. However I'd still prefer it'd just give us something when it expires without breaking at all. Being punished for using mitigation on a tank seems pretty backwards to me. While I'm not saying that you should get a Dark Arts from not breaking it, at least something like some of the MP used recovered or maybe you'd gain some blood. Right now, TBN is literaly a punishment to use DPS wise. It's high risk with no return as you could just spend the MP on directly EoS to maximize DPS. Of course you shouldn't do something like this because you're a tank - but I believe you know what my point is. Hell, Excog on SCH when expired heals too (at leastafter SE realized it's kinda pointless if it doesn't activate).
Okay this might be an unpopular opinion but I do still think that LD is fine as it is... doesn't mean that I'm against any changes however, your proposed changes seem fine to me. I just wouldn't really care either way as the healing requirement doesn't really do much when you usually get healed to full after a tank buster anyway.
Abyssal Drain change is interesting, it's just that I want the GCD version back a lot more. I really liked old Abyssal albeit it wasn't good for single target. It does need a change as it is now. Your idea would sure work.
I... I just feel sad for Salted Earth, it didn't deserve this insane nerf. Might be only me, but it felt good to use in SB. If they don't bring it back as it once was, might as well as combine it with Abyssal.
Okay, just no to Delirium overall. It makes no sense to me why Delirium HAS to be IR, Requiescat, Wildfire or whatever other clone of an ability. Why can't it just be unique? This just a random idea floating through my head now just to prove a point that it can be totally unique and do whatever you come up with while keeping it as a "burst" ability - Delirium would put you into a frenzy/darkess state where your Souleater combo would be replaced with a totally different combo that has higher potency and heck, you could also make it so that the combo has a GCD of 1.5 sec which would also fix the complaint about the "lacking speed of DRK" slightly after the sad loss of BW. I do feel that it would be a little too OP, so you could also add the effect that your Blood drains slowly overtime under the effect of Delirium with no upfront cos (Or some cost, nothing is set in stone). You could also make it a toggle ability that switches you to the frenzy state with the new combo and blood drain, though I do feel that the toggle would mess with Blood spiller a little bit too much... or it wouldn't, it completely depends on how the frenzy combo would act, if it gave any resources or whatever. This way you can have a burst phase with the choice when to use it, so it kind of gives back the feeling of choice that is lacking now imo. Again - I'm not saying that they should do this, this was just to prove a point that you don't have to spam one ability for "Burst". There can be tons of other better ideas than this. GNB has his own unique burst phase already, so why not on DRK too?
More usage of CnS? Oh hell yes I'll take it any day even if the potency every minute doesn't change. It's such an awesome animation after all.