The sword is an ancient weapon, still used by certain provinces as their primary (although usually secondary) weapon for law enforcement. It is widely used throughout the series' as the primary weapon for almost all the characters.
External Link: Xena Sword Reproduction
Strictly speaking, the straight, double edges swords seen throughout the Xenaverse are either anachronistic or not appropriate to the nationalities of the people using them. As a Greek living in the 1st century BC, Xena, Iolaus and the rest would have used either a single-edged sword that curved forward (a kopis or makhaira) or a double edged short-sword shaped like a leaf (xiphos). If the series is meant to be set in the Late Bronze Age a thousand years earlier, then they would have used long, thin double edged swords of bronze, with no crossguards.