Wars in Gaea are fought with only arrows as projectile weapons, and victory is determined by hand-to-hand combat between individual soldiers. Such wars are roughly equivalent to the wars on Medieval Earth. However, from here, the paths diverge and warfare on the tow worlds moves in different directions. On Earth, the development and use of explosives became the determining factor in battle, but in Gaea, the use of floating ships and humanoid-shaped constructs called melefs and guymelefs remained the deciding factor.
This is, of course, because there were no Energists on Earth, but this was also because nations of Gaea have long been competing in development of this human-shaped weapon. This drive to develop them was strongest in nations with an eye on conquest of other, more bountiful nations.
It is easily assumed from the episode where the Ispanos appeared that the prototype for melefs and guymelefs was created by the Dragon tribe. But it is hard to imagine how the Ispanos themselves intended to use the weapon. That leads to the conclusion that understanding the purpose of these constructs is lacking in the people of Gaea. And even Van, who is a descendant of the Dragon tribe, is merely making partial use of Escaflowne's most basic abilities. This suggest that melefs, in the end, may be much more that mere weapons.
No matter what the Ispanos' intentions were, the human-produced melefs and guymelefs were indeed weapons. They came to symbolize the battles of Gaea, where the current level of civilization and culture had been long maintained under control of the Dragon tribe. But Gaea is beginning to see signs of change recently. It is yet to be seen how melefs and guymelefs will develop in the future, or if they will be overtaken by other weapons... The future is still in chaos.