User blog comment:Touchinos/“Last Call” Discussion/@comment-44478361-20191208173429/@comment-34461065-20191209134635

Or the Death Key was justa sort of plot device, Macguffin that was just used during the episode to emphasize on Castiel's "No BS" plicy he has just adopted and is not meant to have any lasting effect on the season, the same way the Shedim were only a one off plot device, or Amy's son, the Amazon's, etc....