The blade is made of soft iron, and is left unsharpened because the edges are used to smash (plaster and wood), eaf-shaped blade and a handle with a ring on the pommel for attaching a rope.
The blade is made of soft iron, and is left unsharpened because the edges are used to smash (plaster and wood), dig holes, and pry. Kunai normally had a leaf-shaped blade and a handle with a ring on the pommel for attaching a rope.