He wasn't implying that Lexaeus used a sword. He was saying that Lexaeus was killed by a sword-user, which was reinforcing his point that swords deal damage in this game.
Xemnas-Lightsabers (Star Wars is just Samurai in space)
Lexaeus-Axe (Tomahawks are axes)
Zexion-Book (To those who understand this, you deserve to understand this)
Saïx-Sword (Claymores are swords)
Tidus-Wooden Sword (he owns your HP)
Sephiroth-Sword







