The Star of David PendantEdit
Vampires who do not mean to harm the person that is wearing the pendant will not be affected by it.
Mitchell as a friend of George is immune to Georges pendant. When Herrick loses his memory he does not want to harm George. So Herrick could get near George even if George shows him his pendant. Herrick only says that he does not have any prejudices against Jewish people and doesn't seem to be affected by it in any way.