I'm the guy who mentioned the Kustom King Broadhead File. I discovered years ago that this file has a fairly smooth and rounded edge, instead of the usual flat edge with file teeth. I use that rounded edge as a steel. I file-sharpen a head until it's cutting arm hair. Then I hold the file 'edge-up' and stationary (left hand) while stroking (steeling) the broadhead edges. I have my own very specific technique as does everyone.
One of the tougher things for most guys...when it comes to files...is sharpening free-hand while maintaining a consistent angle. When I reach the point of filing "this edge...flip, other edge...flip" and doing one file stroke per edge, it can be hard to maintain an angle. I have no secret for this. I've been doing it for so many years that I can just free-hand file from rough edge to totally hair-peeling sharp.
I don't know the maker of the KK file. Pretty sure it's not a Grobet, and for sure not a Nicholson. It's made in Portugal and stamped with a 'W'. Great file.