Why cant you sharpen a a military bayonet?

Most bayonets are little more than a steel bar disguised as a knife. The angel of the bevels are generally far to obtuse for a fine edge. The hardness of the steel is often low to give greater toughness for the increased leverage it experience when mounted on the end of a three foot handle(rifle). baynets are spear points basically, & spears poke holes. A Bayonet is best used to thrust it's point into the target (make holes)