Hawkeye Idea
I mentioned this with BP buff, so I will here again as well. Instead of giving him different arrows for different things, just give him massive "rupture" damage like Tigra. No one, that I know of, is immune to rupture. That, in itself, would be a good start to his DOT problem, with switching out different arrows.
Man, I hope this guy is good. It will definitely be setting out the precedent of all the OG Avengers moving forward.