ToME: the Tales of Maj'Eyal

An item ability bound to the hotbar from 'm' rather than dragged from inventory will show the icon for Charm Mastery instead of the item. Also, once used, it goes slightly grey and displays no cooldown number; when dragged from inventory and has the regular item icon it goes red as intended and properly displays the cooldown.

edit: also it seems if you have the no-cooldown-listed charm mastery icon version then when you unequip the item the icon vanishes from the bar entirely.