There are a series of locked doors and chests related to the Sanctified Amulet in the Regalith Grand Cathedral, a main story dungeon in Metaphor: ReFantazio. Here's exactly what you need to do to get ...

First and foremost, all amulets in The Lost Crown are fairly weak until upgraded. To upgrade them, you have to visit Kaheva’s Forge in The Haven and bring her Azure Damascus Ore and Xerxes coins.