User blog comment:B214/High School DxD BorN Episode 9 Review/@comment-23847729-20150601192532/@comment-26322543-20150602025848

The past possessors died because they activated it in the first place. It was never said Belzard and Elsha could use it.

When Valid came he said that it could be reversed only because it was incomplete. The complete version is completely inescapable unless you can control it, and Valid is the only one who ever showed being able to do it.