Why would anyone stun it after exsanguination. It would already be dead.
'Exsanguinating' is what I said. It's a process. You can certainly stun an animal once you've severed an artery that is going to cause them to bleed to death. That's really what this whole ordeal is about. Ritual killing doesn't allow it before exsanguination, well at least the Halal version doesn't. Not sure about Kosher.
Now as for stunning it before hand, why would you want to do that when stunning can cause more trauma than exsanguination.
The trauma is kind of the point, exsanguination is trauma too. If you stun an animal properly with percussive stunning, then it is unresponsive. There is no nociception-the pain processing pathways- when the brain can't process signals. If you start to bleed an animal while it is still conscious, then it will sense the trauma of bleeding to death....from a humane standpoint there is no better method than to stun quickly and efficiently before doing anything else.
I'm not denying that the animal likely suffers at least in some cases through exsanguination, but stunning only increases the chance of trauma.
Trauma is just a physical injury caused by something external. Exsanguination
is trauma. Anything you do to kill an animal will involve trauma. Trauma is not the issue, the issue is the animals awareness and processing of physical stimuli related to what is going on. Stunning before bleeding is far more humane.