Although there are some perks to having a unique annimation rather than object annimation in a single player game, It is generally a better practice to simply stick the camera on your face, and animate your model's hands. In this way you can more easily adapt this to NPC use, as well as not look stupid when(if) your gamers go online and don't understand why their weapon annimations look different than what others are doing. Also, this approach doesn't restrict you to using your code for Player Characters, as it would have no added code for displaying the knife's swing, which a NPC obviously wouldn't care too much about