"Did you figure out anything yet?"
"No, unfortunately."
Sitting beside Celestina after sleeping for 2 hours, I was examining her staff with all my focus, trying to understand anything about it.
The soul-bound artifacts were made completely of soul essence even though they looked otherwise, they weren't just like souls, but literally part of them. I only knew this after seeing how Celestina's soul density was decreasing everytime she summoned her artifact.
That was why they can never be destroyed and can always fix themselves, they were like soul injuries that only need to regenerate.
When an Exalted or a cultivators summon them, they come out of the soul as soul threads before gathering into their physical form, while what keeps them connected to the original soul is the part of the soul threads that stays spectral.
When someone dismisses their artifact, it simply dismantles into threads again and returns to the soul before merging with it.