Sounds like a bunch of bizarre stuff happened in that encounter there... but the most bizarre thing to me is Lohse swinging a 2H hammer around...
IIRC, there was a persuasion check during the dialog and in my playthrough I passed it, so the fight went on normally like any other fight for me.
I'd say that: either there was a way to dispel the "charm" thing you described, but you didn't figure it out before killing her. Or, there really wasn't - your Sebille was gone for good - this situation wouldn't be unique in this game. Why would you think it's not logical?
Have you tried talking to the Prince of Shadow's spirit? He might have something valuable to say.
