Some weapons are good enough to keep on all 3 characters. I don't know if I'll buy a gjallahorn seeing as I have 1 maxed, but I have icebreaker on all 3, and the bungie app could be better. For example instead of moving weapons to the vault, why can't I move a weapon directly from character 1 to character 2? If I could do that I may not keep extras of anything. (And if that is possible I would love to know how to do it)