It would appear that this tool is made with some kind of high quality tool steel ... possibly up to the same as the grade 8 that is mentioned as the highest it should be used on for hardness. Somewhere around rockwell hardness 70.
It has some kind of "coating" on it with a supposed hardness of 92, to make the tool's edge work more efficiently in removing the thread and burr and helping keep the tool's edge sharp.
If you have a small diamond file, you could probably get in there by hand and re-sharpen the edge from the outside...
It says that it cannot handle Chrome/Moly steels, however ... which might actually indicate that the material that it is made up of may be lower in hardness to it or the same.