"The Phantom Sword is no ordinary sword... When forged, normal metal can never handle that kind of sacred power! Aquanine... Azurine... And Crimsonine... These three pure metals must be forged together to create the Phantom Sword."
The Pure Metals are items from Phantom Hourglass. There are three total: the Crimsonine, the Azurine, and the Aquanine. They all hold a sacred power that can be used to forge the Phantom Sword. Zauz is one of the few people alive that know how to unlock their powers.