Spy knife idea

A knife that charges your invis watch when you get backstabs and then keeps you invis when backstabbing or has the cloak and dagger style effect when you are moving and invis, your watch has no use until you get the backstab and you go auto invis with it when you get a kill similar to the YERs auto cloaking. i have no art of this or any naming ideas so feel free to go nuts with that