What happens?
1 - Illegal to apply Mitosis to any weapon; invalid target
2 - Valid target but nothing happens
3 - Creates a new flying weapon
4 - Creates a weapon in the weapon slot
5 - Creates a weapon in your hand
The answer is (4), it creates a new weapon in your weapon slot.
Decent :life combo with Lifesmith, I guess?
Behavior was a bit of a surprise to me. Not sure if it's intended or just a consequence of playing a weapon without the applied traits.