Blacksmiths hot cut tool made of H-13 on a mild steel handle. H-13 is a hot working steel designed to be used hot and keep its cutting edge. Made to be struck with your hand hammer to cut hot steel. Though small in size it's capable of big work. I even use these under my 112lbs air hammer. The edge profile is called a walking chisel. This allows for gracefully stopping and starting lines. An essential tool for every smith.
A few seconds of video of one in use.