Not real sure what you want to know
looks like a pretty good mess,first you need to let it dry,I would clamp it to something straight and put it in a dry place for a while,next you really need to clean up all the tool marks,nothing wrong with
roughing one out with an ax,which it looks like you did but you need to clean it up after you have done that. :)Other than that I would say no to the fire harden,
just let it dry and re tiller.
If it holds in the fard where you cut the handle out you will be lucky. Just a question,why didn't you just leave the back flat all the way through the handle area ?
Pappy