Board Thread:Episode Discussion/@comment-14138255-20160214165601/@comment-26397825-20160217132729

Hang on, let me grab the transcript.

Winter : Excellent form! Now think to your fallen foes! The ones who forced you to push past where you were, and become who you are now. ( as the glyph flickers in and out of existence and Weiss grimaces in concentration ) Think of them, and watch as they come to your side.

So...obviously something happened in her past, perhaps when she was just starting out, that involved Beowolves and Nevermores. And it pushed Winter to move forward from what she was and become a different person.