The Sign of the horns is a well known gesture at every heavy metal concert. It doesn't have much in common with satanism... it's about revolting against rules and narrow-minded believes.
Don't get forced in what you have to believe, in what you think, in what you say! You can practice this even without listen to heavy metal music! ;)
Note: Prints, even the "rough" ones, are kind of shiny. If you like more an antique look, you can do this easily yourself. For brass and bronze you just have to put it on a hotplate and throw it in a glass with olive oil after that.