Friday the 13th: The Game

Throwing knives can be found in the game stuck in the side of some cabins or in a tree and lamp posts, and all you need to do is press the A button to pick them up. It does not have to be done in one match it can be done over many. To throw a knife you need to hold LB to aim and then let go to throw the knife, you DO NOT need to kill them just hit them. Repeat 12 more times and the achievement will unlock.