I'm not offended. Believe me, I gave this question a lot of thought!!! Humane is an awkward word in the regard of dispatching of an animal for food. I don't think of myself as a "killer" and yet this is the transition the animal must pass through to fulfill its intended role. I feel it is my duty to perform this act as swiftly, skillfully and with as much respect as the animal deserves since it is giving its life to feed us.
My primary career was as a paramedic for 15 years. Using what I learned doing that, I am comfortable in harvesting my animals the way that I do. Have you ever passed out? It happens quickly because of lack of blood pressure to the brain. Cutting the throat causes immediate and complete loss of blood pressure to the brain. Putting the bird upside down causes all the blood to rush to their heads causing somewhat of a stupor and will speed bleeding out. A razor sharp knife is used because a quick cut with a sharp blade is less painful than a sawing cut with a dull blade. Have you ever cut yourself with a razor blade and barely felt it until later? This procedure ensures that the heart continues to beat until all the blood is pumped out resulting in complete exsanguination. A further step can be taken to 'stick' the bird through the roof of the mouth destroying the brain stem. Death is in seconds, unconsciousness is nearly immediate, nerve reaction is all that can be seen.
Why am I not a fan of decapitation? I used to do that when I started but personally I did not feel that they bled out as well since they weren't hanging upside down. Also I like the way the cone keeps them from flapping all about.
As I said, it's just my opinion, but I've put a LOT of thought into it!