Sindri

I personally use a wire wheel on my angle grinder. (This probably doesn't help much as it is 4 years later but I figured I'd throw it out there)

well I'm 12 years late buuut I recently made a horse shoe knife and hardened it in water, didn't temper it. Honestly it works pretty well so far, not a shave your arm kind of knife but it's alright at cutting cardboard, burlap, feed sacks, leather food, etc., probably wouldn't use it to chop wood but it's too small anyways. The horse shoe was over a hundred years old though so it's possible it was something somebody made from a scrap of medium carbon steel as opposed to the low carbon in mass produced horse shoes now a days. Idk for sure though tbh, just that it's an over a hundred year old piece of metal and that it works ok for what I want it to do