This picture shows the sword of Jon Snow’s that made out of valyrian steel and the ravens that fly around it. The nights watch symbol is the raven. By this picture it proves that Jon Snow’s watch has begun. Then he was the Lord Commander of the “nights watch”, Jon Snow has the only right to command and to rule the “nights watch” to protect the wall by not letting the dead attack the leaving. Jon Snows sword is made out of a rear steel valyrian steel. This steel even can kill night walkers. In this series we can easily recognize Jon Snows sword by Ghost’s (the direwolfs) head on top of it. Ghost is the direwolf of Jon Snow.