As a Nightwolf main, I can say for sure that the arrow is absolutely useless against a seasoned player. Everytime you hit an arrow, you probably could've went for ex lightening instead. It starts up too slow and recovers too slow, so it's only really safe from full screen against someone who can't teleport or counterzone, which is only like.....maybe eight characters?
I wouldn't really count the lightening as a projectile, it's more like Quan Chi's runes except if it autotracked, was unblockable, and was much more balanced then it appeared on paper.