User blog comment:Woest/Chapter 382: Alegria/@comment-7418318-20140428142125/@comment-24066070-20140428173605

@Nick: considering the many situations where FT members and allies should have died, it would be rather strange if the author suddenly decided to permanently kill off a Celestial Spirit (which should have far more vitality/ survival chances than a human), so I doubt you'll have to fear the death of a Spirit :)

While Silver did say "this magic..." and the fact that he is a big mystery could mean he recognized her magic, but I doubt that was the case here. He likely just sensed someone's magic just like Kyouka and Marde did.