Instead of buffing Zed's generic line skillshot, could you make it a little more unique?
Like maybe let the Shadow Ninja do Shadow Ninja things?
I'm talking like WQW so he creates a shadow behind his target (or the closest available hex to it) and throws two Shuriken at his target (more total damage than current, so he's more of a single target type assassin with some AoE splash) and swaps to the other shadow.
We've got enough line skillshots in this iteration of TFT.