steel acts just like iron, until a blacksmith "heat-treats" the steel. this is a special way to make the steel hot and then cold, so that the steel will become hard enough to keep a cutting edge (blade). a blade made from a piece of iron (instead of steel) will very soon become dull and will not cut. good blades (for knives, chisels, axes, and other tools with cutting edges) are always made of steel, then heat-treated, and then sharpened.