Don't think anybody other than asuras can handle that mana. Any human (Ellie or lances ) will die. I believe it'll be for Arthur himself(for his mana core) or maybe Silvie. Arthur has an asuran physique.
Remember when Arthur could not use more of Silvia's will because he was a human and his body was breaking down. It cannot be trained.
I see Arthur using it on himself, that's why he grabbed his sternum
What if Arthur uses it to heal his core so we can use mana again. Mana and aether?? Maybe.