I also dont see this as a sooooooo OP card. Of course, with weapons its powerful, because, like said, you are supposed to have 1 weapon, and because of this they are cheap. But worse, using Mitosis you arent generating a card, but a 2 card combo. So, Im also up to deny Mitosis being played in animated weapons.
But I already see that a deck based in animated staves and adrenaline is powerful, isnt it? If can generate like 60 life per turn pretty easily. However, you are safe if you have a shield, and can build your damage or win by deck out. There is always a weak point. Flying swords deck? Sure, but the generator is a weak creature that can be eliminated easily without a quint. An Otyugh, for example, negates completely a Mitosis flying Sword. Im not really worried with these (a dragon + SoR spam with some stall worries me much more), but, because of too much card advantage (generating 2 cards combo using 1 skill), I also think it shouldnt be able to target weapons.
Other than that, maybe 6 cost unupped and 5 upped would be better. Its currently too cheap, you can pay with 2 SuperNovas or your mark, and you wouldnt even need other Life quanta in your deck.