Thing is, the sword was not the standard battlefield weapon in most cultures. Whether we are discussing European knights, Japanese samurai, or any other historical pre-gunpowder culture, the infantry weapons of choice were spears or various polearms.

I think the real allure of the sword is rooted in a few factors:

1. A sword was the preferred backup sidearm of the soldier and the civilian's best weapon for self-defence. This is like the modern pistol, and distinct from daggers and other knives even though various smaller blades are common weapons throughout history.

2. Legendary swords of myth and legend lend an aura of supernatural power to the idea of the sword. See the list of historical and legendary swords and the list of fictional swords at Wikipedia.

3. The spectacle of the duel on stage and screen also maintains the aura of the blade in pop culture. My name is Inigo Montoya. You killed my father. Prepare to die.