I got one that's even better:
Any weapon (or exotic?) should work on all Champions, but just make some weapons better so you always have a choice what to use. If you see all three champions in like a GM you have to switch to weapons to be able to stun them. I want to use the weapons I like, not the weapons I have to use because someone decided it's now time to use that one, that one and that one!
ps Sweet Business should be buffed and get explosive rounds, firefly, tombstone, threadlings, void balls and Lightning added to each bullet!