At the Grenth task region in Siren’s Landing, when a ley-line scavenger is killed and the 4th skill (“Transfer Magic”) used to channel magic to Grenth’s reliquary, even though the skill bar is reverted to the normal equipped weapon skills, the backpiece on your character does not reappear, even when out of combat. You need to enter the Hero panel and uncheck and check again the visibility for the backpiece for it to show up again.