There some legendaries that are too good to be legendaries but not unique enough for exotic, and some exotics that are lackluster compared to other exotics. A solution for these items could be to add a rarity between legendary and exotic. Put the mediocre/gimmicky exotics in this tier (Aeon armor, Starfire Protocol, etc.) so you can do combo stuff like Mk. 44 Stand Asides with Skullfort, without giving up the exotic slot. Putting certain legendaries (Pinnacles, mostly) in this tier will allow them to remain strong, and also be justified for their strength as they are no longer competing with other legendary weapons. Just spitting out this suggestion.