The iron knife is a ranged projectile. A Ranged level of 10 is required to wield this throwing knife. To create throwing knives, the player must have at least 22 Smithing. Each iron bar creates 5 iron knives, granting the player 25 Smithing experience. They are low in demand with the buy limit so small, people look for other ways of getting experience.
Iron knives can sometimes be found inside barrels.