I have seen these type of axes break in this manner. Usually such a 'trauma' comes from missing an intended target and hitting a rock or other very hard object. As has been said more than a few times, it boils down to whether you really want to spend the money to have a smith repair it.
You could just reprofile the blade and use it as it. Back in the day, many of these were just filed off and put back into service. On smaller chips/breaks, I have used a belt sander to put them into working order. The short answer is that it probably is not worth fixing, but it can, with great effort and expense, be accomplished in the hand of a master smith.