It's a really bad ultimate upgrade. Perhaps it could be slightly improved by replacing the current explosion with the spark of life explosion+stun+knockback.
I also thought about giving the vengeful cloak the ability to "death mark" enemies like Recon Rangers, but that would be crazy overpowered.
Trouble with the current one is that the explosion is super small requiring players to be in Cutter range to get the most effect
Give it more range and the ability to deal damage with the blast and it could be quite useful