We had in my opinion 3 correct replies Ide have to say sandpaper of one sort or another has to be the most used item in any shop. I have been sanding this or grinding that and its all sandpaper related. I would have to say 80 percent of knife making except for forgers is done with sand paper. Yes files do have their place but arnt used nearly as often as sand paper. Every time im in the hardware store im picking up a few sheets of paper. lol
In no particular order, KMG, bench vice, sandpaper, EDM stones. I forge, but because I am not able to take my blades down to 99.9% of final shape, I do a fair bit of grinding. Also, as I haven't really fugured out how to grind much above 320-400 grit with creating divets, I do a LOT of hand sanding.