Board Thread:General Discussion/@comment-6986530-20131211045616/@comment-6192846-20131228142254

That's the idea I think is being hinted at (and that really sucks that Chartette's hide the swords plan was so good it duped Elluka). If any vessel being split into multiple parts allows the demon to freely jump to any piece, then Elluka may have simple thought she had the real vessel (sense the "Sin" from it), took it, replaced it, sealed the scissors, then went on her merry way unaware the demon just jumped to its other half and possessed Kayo anyway.