The status.

The Coffin is whole as a relic which was never known who, where, and how was founded it was just there since the beginning of the vault, but for reasons unknown to no one known but the wielder of the vault Elizabeth Delvor never give it to anyone or was forbidden to touch, maybe even she didn't know that altar and the coffin were one as whole or simply chose to not delve deeper because as a light user, she is uncomfortable with Darkness.