The witches weren't actually hypnotized. They were merely shocked and were unable to believe what they were seeing.
In all the history of witches, there was never a silver-haired male witch. And there was only one silver-haired witch at a time. Unlike the vampires, witches didn't have a royal bloodline. Once the current queen starts to weaken, the queen's power will be slowly transferred to someone among the witches. The current queen cannot choose her successor either because the witch queen's power would be the one to choose its next host. The witch who will receive the power will start to have some changes in appearance. Her eyes and hair would turn silver, which would be the ultimate proof that she was the next chosen queen. To the witches, the silver hair was the crown of their ruler. A crown no one could take away by any force.