I agree, I would like to see this fixed. If you make an event item, please flag it as storable in armoire.

I have a similar problem. I had the Lunar Summer Top and Lunar Summer Trunks in my Armoire and the event NPC allowed me to purchase another set. I can't store, discard, or trade the extra set, so it is taking up space in my inventory, my retainer's inventory, or my armory chest. The GMs haven't responded yet and I would like this resolved. Please make this sort of thing discardable.