Ashe's new W
Why not make it so if someone takes multiple arrows they at least take slightly extra damage per arrow? I get you want them to be able to block shots and that you don't want it to be too OP at close range, but what about something like +5%-10% damage per extra arrow?
My reasoning is a lot of the time from a practical standpoint it's probably going to be a tank taking extra arrows and they have the armor and health to deal with it. Option B is it's probably an assassin who's going to 1 hit Ashe anyways so why not give her close range counterpunch to leave him just a little bit lower than he would be?
IMO if you are going to make it so that more than one arrow can hit someone, the skill is a shotgun skill and it needs to work like one.