Xiphos

Ancient Greek warriors also carried short swords, called xiphos, as a secondary weapon. They were used when spears snapped or were lost in combat. They may have also been used when a hoplite needed to discard his spear and shield in order to chase down routing enemies. The xiphos usually has about a 2 foot blade; however the Spartans blades were often only 1 – 1.5 feet long. This shorter xiphos would advantageous in the press that occurred in the front row when two phalanxes smashed together. In this crush of men there was no room to use a longer sword, however a short sword could be thrust through gaps in the enemy's shieldwall and into an unprotected groin, armpit or throat. Smaller xiphos would have been particularly useful during the Peloponnesian War (431 BC - 404 BC) when many hoplites began using lighter armor, even abandoning it, in favor of mobility. Alternatively, Greek warriors could carry the curved kopis, a particularly vicious hacking weapon that earned it a reputation as a “bad guys” weapon in ancient Greece. Spartan hoplites were often depicted using the kopis instead of the xiphos in the art of their arch rivals the Athenians.

All credit and sourcing to: http://www.ancientmilitary.com/greek-warriors.htm

http://www.army-guide.com/eng/images/xiphos1365744059.jpg