The Broad Swordsman is stronger than the Short Swordsman and is an upgrade
available immediately after researching the Short Sword. Only three civilizations in the game cannot upgrade to the Broad Sword. It has more hit points and attack, making it useful in the Bronze Age, being better equipped to stand up to cavalry. However, their speed still poses a problem, making them vulnerable to archers, just like Short Swordsmen. However, they do make a good army in massed numbers for a Bronze Age assault.
"The appearance of bronze short swords led to further advances in weaponry as competing cultures sought an advantage in military technology over their neighbors. Where the early short sword was primarily a piercing weapon, the broad sword evolved as a slashing weapon. The width of the blade increased strength sufficiently to support a slashing attack that could cut into armor and break short swords designed for stabbing."