Vendor: If it's REALLY silver, like solid, pure silver, it enhances mental, magic, and physical powers. In fact, you might be able to use it to block whoever you don't want contacting you from contacting you, as long as you wear it. Obviously it would provide protection against werewolves, and by extension, anything that's a werewolf hybrid.
Really...
Vendor: The thing is, finding one made of pure silver and that has been made under a full moon is pretty hard. Yeah, you got those store bought ones humans wear to try to act cool, not knowing what they are, but those don't have any kind of special properties to the extent a real one has.