Modding Help Rendering sprites over the player?

Just as the title says, how do I go about rendering sprites of, for instance, weapons and throwables over the player's bodyparts, in this case, the arms?

 

You cant. Its all handled by the engine and there is nothing you can do to change that.

 

You mean make a custom weapon and get it in multiplayer, or override your character's body with a custom armor(For example)?

You can do the first one.