Truth be told, autohits don't suit physical based void assassins, 160% Weapon scaling is a lot, and so is an innate damage steroid, but that doesn't mean a whole lot to VAs when they scale from crit damage exponentially, being their weapon scaling and primary damage source, on top of this...
daggers boast low power, but not the best of scaling, they have no steroids like weapon power or 2hand or passives to boost their scaled weapon attack.
So in short, the scaling on the skill is nice, the innate damage buff is also nice, but daggers simply cannot pull off this skill correctly, and they never really will..Infact the only daggers I can think of that can pull off this skill is probably a mutated Brawler's Glove and a mutated wooden Katana, and I know how much you love Mutation.
In that sense, I actually think this skill would be better off suited as a basic attack skill with a damage steroid on it, suited more towards killing a target and reaping rewards for doing it correctly.
Here's what I suggest:
Becomes basic attack(s) (Split across two hits, slash and pierce)
Both basics gain Hit and Crit equal to Void Energy.
Gains damage equal to Rank*4% of the target's missing health, and is doubled when sneaking.
Has a 3 round cooldown.
And just to make sure this is in here too, cause these effects were cool and I really prefer they'd be kept:
1 Range, 7 when Airborne.
If eliminate kills a target, the cooldown is refreshed and all targets gain fear permanently.
What do you think?