User blog comment:Hidden Scorpius XI/An ever-present detail/@comment-25555436-20150120183702/@comment-3257939-20150121000419

So if Weiss also takes off her tiara (which she only does when she's on her pajamas) then hell would break loose?

Yeah... that sounds kind of over the top so I'm just going to believe that it has some special meaning like Ruby's cloak. Maybe it was a present from her mother.