I agree, it doesn't even have to be an active ability but i believe it should be something related with stealth/shadow dance.
Shuriken storm = more combo points = more finishers = more shadow dance charges = more chances to use our aoe talent.
A few examples...
It could be a passive talent that adds a shadow explosion to shadowstrike.
It could be a passive talent that makes our next nightblade after exiting stealth affect all nearby targets.
It could be a passive talent that adds a big chunk of shadow damage to shuriken storm while stealth is active.
And of course, it could be an active finisher or just an active ability, but honestly... i don't think that throwing more buttons to the problem is a way to solve it. AoE tools shouldn't differ too much from your regular toolkit and rotation, specially when we just want to be able to use the spec in all scenarios while we are fully aware that AoE is not our speciality.
BTW, a friendly reminder that death from above, while it sucks, it's actually half an aoe finisher