Heir-stone

Bad Times' talisman.

My thought is that this was a ceremonial necklace given to him as the prospective heir of his family. When he became cursed into his cat-gremlin form and was rejected by them, he lost his status as Heir - but they were superstitious about destroying it or giving it to his replacement sibling, and hid it away and made a new Heir-stone instead. After he was an accomplished thief he went back to claim it to make a point, but this may have been a bad move as there were... spells on it he had not anticipated...