Also using Draugr Polymorph allows you to keep bound armaments active, as long as you activate polymorph after activating Bound Armaments. But other outfits do not allow the same thing. And after initially applying an outfit, once it goes off and you go back into the collectable UI it still has the outfit checked, so to reapply it you have to put it away first then reapply. So i dont know if it is suppose to ''put away'' itself when you do something to take off the costume, but it seems to be a redundant step; its already off and to put it back on you have to put it away then take it back out

Edit: @ZOS I hope it can be changed so that the costumes can be worn over Bound Armaments, that way someone doesn't have to constantly see themselves in the same looking armor all the time