Well, some movies and series say silver would be good against vampires. I mean, don't be ridiculous. Vampires? Whats next, trolls are allergic to garlic? As the deamon hunter you are, you certainly aware of the fact that silver is a good weapon against werewolfs. 
Be informed: the particularly sound which comes from this silver whistle is not yet tested against the evil forces so be careful, full moon is rising soon.

 

Silver whistle, manufactured via shapeways.com 3d printing service.