Since everyone seems to be interested in Legionnaire trivia, there was an interesting reason for the construction of the pilum as well. As you can see, about the last three feet or so of the spear is a mild iron, which was supposed to stick in an enemy shield and bend. The iron shaft kept them from hacking the shaft off, so the shield would become useless. They would have to discard it, or the Legionnaire would step on the shaft of the pilum, pulling the shield down and opening them up for a blow from the sword.