While I generally agree with what you say, I’d absolutely hate this form of Spirit Bomb. You directly compare it to Seraphim, which does sacrifice a good deal of tankiness(2 charges of SotR), but you also gain a tiny bit of passive tankiness from the secondary stats provided(Crit=Parry, Haste=GCD, Mastery=Consecration damage reduction and block. Minor things, but they are there).
I’d be all for Spirit bomb losing the heal from consuming the souls or the frailty debuff but losing both basically makes it completely worthless, especially if our Souls would be completely RNG. You have acknowledged several times that our TPS and damage is trash without it. Yet, you also feel okay with removing its heal, removing the debuff and making it a psuedo ranged spell that we may or may not be able to use it when we need threat and damage the most?
It would literally be worthless and not even an option in that form. At least, that’s my opinion of course.
Could work. Though I’d kinda like something like Chaos Brand to be tweaked into Vengeances Mastery. (leave the debuff as is for both specs,). Like, change our Mastery to Demonic Brand or even Charrged Warblades. "Enemies afflicted with Chaos Brand do X% less physical damage to you(halved for magical affects). Additionally, heal for Y% of all fire damage dealt.(with a cap, obviously).
I dunno, probably a horrible idea but, outside of the attack power, our Mastery is completely worthless. It needs either more passive mitigation built into it, or more affects. If not both.
Bears get more health, receive more healing and get attack power. Paladins get damage reduction in Consecration, increased block and attack power. Warriors get increased block, increased critical block chance and attack power. Monks get stacking dodge when hit or using Blackout Strike(resetting on successful dodge) and increased attack power. Blood DK’s get a % of Death Strikes heal as a physical absorb shield and attack power. And then we have VDH, we get attack power and a buff to Demon Spikes.
Arguably, Blood DK’s and VDH both have weak a weaker mastery(compared to everything else) but at least Blood has something that is always useful, even if it doesn’t feel impactful(though it can be pretty good at reducing physical damage taken in the long run). Our Mastery may as well be “increases attack power by X”. So yea, why not merge our Mastery with Charred Warblades and give us something else, maybe increased Parry(since shield folks get block), or damage reduction added onto our tattoos. We are Parry based tanks, one would think our mastery would reflect that, just like Warriors and Paladins get a mastery that reflects their blocking ability. I dunno, we need something though, you know?
TLDR: Probably bad ideas, sleep deprived. Rambled. So it goes.