Using bones you have in your hands you channel a small amount of Necrotic energy into the bones changing there shape. If you have one bone that’s a foot long it creates a short sword, if it’s two bones that each is one foot long each you can create four daggers or two short swords. Each foot of bone is two daggers or 1 short sword. If your DM allows it you can use longer bones from animals can create a long sword or great sword.