Wearing a minor faction's breastplate and helmet caused a reproducible lockup after every combat. Also, I couldn't equip any other armor after equipping them. When I took the armor off, I couldn't put them on again, and still couldn't put on any of my faction's armor (until I reloaded). When I traded the armor to another champion, it didn't show up in her inventory but when I sold it to the shop it showed up in her inventory in the shop window.