Exclusively iron files are a thing, they just didn’t make for as good a screencap, cuz they look like pressed turds. The point was only that stone isn’t the only option for grinding. An iron file used on some other iron surface would smooth out the scaling on the file pretty quick; but it’d also do a bit of actual grinding on that surface as well.

So, it’d take a lot of grinding, most likely with many file, but you could 100% sharpen an iron edge with an iron file. …and tbh, lots of grinding with many tools fits the theme the thread perfectly!

I mean, -that- file is more than just iron, but it’s also more recognizable as a file. Exclusively iron files are a thing; they just look like rectangular turds.