If you know how to, and if you practice, you can use playing cards a weapon. I am not going to teach you how to do that. In this Instructable I will show you how to throw them. Also, keep aware that you will destroy and lose many, many cards while doing this.
Just to mention, my camera is not great and I find it difficult to take photos with one hand, that is the wrong hand, and the camera is designed for the other hand.
*Ok guys, update! As it turns out, this way is wrong. It works, but is apparently my own adaption of a different way. Without overcomplicating it, your arm should be vertical, not horizontal.*