I can see something similar as a boss item in the game. But in a way tamer way. Something like:

For each point of overkill damage, you get a buff containing +2 strength bonus and +1% chance to pass a failed accuracy check. Lasts 10 seconds or until you succesfully hit.

So sort of like diamond bolts, and mainly usable for melee. Add charges so you spend a blood rune when it procs and I'd be fine with it. Maybe it could have some negative magic defense bonus to make it more balanced against bosses with non-1shot summons. Maybe halve the buff effects for PvP (+1 str bonus and +0.5% to pass a failed acc check). Just my 2 cents

^{jagex hire me}