The first stitches I ever received were actually to my left forearm. I was fishmouthing the end of a piece of tubing for a recumbent tricycle I was building, using a half-round file (with a handle!) and the file slipped off the tube, my weight carried my arm forward against the very sharp beveled end of the tubing and I neatly filleted my arm. I could fold back the flap of skin at least an inch. I'm looking at the scar right now...
I find I get much better control in holding the file by the body. Like in draw filing, but I hold files pretty that much now for all filing. Of course, needle files have integral handles, and I use my thumb and first two fingers to control them.
I suppose I am a fairly odd one also in that I mount my hacksaw blades with the teeth facing the handle so I cut on the pull stroke...
Best regards,
Randy