ToME: the Tales of Maj'Eyal

I have a body armor with an activatable ability equipped (Cloud Caller and Eel-Skin Armor), and when I bumped up Defiling Touch to level 2.0, they gained the "(Nightmares)" attribute, which I guess means they are "different" objects, as their hot key icons became "?" unknowns.

To fix it, just drag them from inventory to toolbar.
They didn't become different objects, but the toolbar stores item by name for historical reasons, and the name changed.