Right.

Ailsa looked down at Ryu's chest. She knew that she had to pull the stone out or else Ryu would never heal. But, if she removed it, then considering Ryu's state, his soul would definitely dissipate. 

The best choice would be to have Esme kill Ryu, but without Ryu controlling her, there was no guarantee that she would be able to sever his link cleanly and without harming Ryu. 

Ailsa should be able to take control of the daggers to do it personally, but this was Osiris, she didn't have access to her strength here since she was entering through her special ink with Ryu. If she didn't have access to her qi, she obviously wouldn't have access to her Spiritual Qi either.

'The alter…?'

Ailsa suddenly remembered the situation of the young woman Ryu put out of her misery. Back then, she had been lying on a stone slab. Obviously, she hadn't had a stone lodged in her heart, but her soul still hadn't dissipated.