And by the thing I mean possess Ardbert's body.
We know from the Cardinal Virtues quests that Vauthry raided the graves of the First's Warriors of Light and turned their corpses into Cardinal Virtues and spread the sin eater blight across the realm.
Why did he not do so for Ardbert as well? Was it a matter of could and chose not to, or couldn't?
Either way, his body was left ripe for the taking by Elidibus, who we learned from Anamnesis was the heart of Zodiark and thrived on that desire to save the world. Why did Elidibus not possess Ardbert's flesh from the start, if the people's hopes for saving the world are what empower him? Was it something to do with his shade still hanging around?
I feel like I've missed something important here.