What magical item does Maui use?

Maui uses a magical fish hook.

In Moana, Maui's fish hook is both his signature weapon and the source of his shapeshifting ability. With it, the demigod can transform into animals and other creatures, although controlling those transformations becomes difficult after he loses confidence in himself.

The hook was lost in the ocean after Maui stole the heart of Te Fiti and battled Te Kā. Moana and Maui later travel to Lalotai, the Realm of Monsters, to retrieve it from Tamatoa, a giant coconut crab. Maui initially struggles to use it properly, but Moana helps him regain control.

The hook is badly damaged during the final confrontation with Te Kā. Maui fears losing it again and briefly abandons Moana, but returns to help her. After Moana restores Te Fiti's heart, the goddess repairs the hook. The item is inspired by the fish hook associated with Māui in several Polynesian traditions, though Disney's character combines elements from many different Pacific narratives.