Glad to see you actually did legwork, and hope you did not assume I was calling you a dimwit, as one never knows how much experience a person has prior to posting questions, and I was approaching the answer as to a newbie. As sure as I assume deeper knowledge on a subject, am invariably wrong.

As DS mentioned above, some files simply nitrided or otherwise surface treated for extreme hardness on exterior, and some of those only ruin steel for forging as the surface treatment ruins homogeneity and impossible to forge. Did you work as a farrier, or are these just for hoof trimming as an owner?