The Broad Sword is an upgrade available for the Barracks in Age of Empires and is available in the Bronze Age.
Before the Definitive Edition, it was available to research only once the Short Sword upgrade was researched to unlock the Short Swordsman.
Once the Broad Sword is researched, the Short Swordsmen is upgraded to the Broad Swordsman.
Broad Sword is available to all civilizations except for the Egyptians, Greeks, and Yamato.