User blog comment:HazelQuill7445/Awesome fan art/@comment-27106917-20170913001944/@comment-34633327-20170913035506

I'm not sure if that was there intent, but Weiss having an emotionless expression may be due to the Knight Summon. Since her summons seem to be affected by her emotions, it would make sense to try and maintain them so as to attain better control.