With it as a projectile it would be harder to achieve making it as consistent as the player. Plus you would have the chance to counter it with matrix.
Maybe have a charge up that affects how long it lasts? with a damage threshold that would cancel the ability if your too greedy?
and as compensation make her faster in invis with some more dmg.
EMP has a charge up and controls the area you throw it in, and if you land it on a player it follows them.
Just my idea since I see alot of people complain about hack, interested to hear opinions.
I think sombra with knives was also one of their early concepts.