War was probably the only thing about humans that never changed no matter how much time passed. Of course, war itself would change in its form and combat methods as generations passed.
Back in the first generation of Eich, although the power level of those warring on both sides was ridiculously high, everyone fought using the simplest and most direct methods. In fact, many existences on both sides would even fight each other bare-handed. Battles were just like street fights between unarmed hoodlums, with punches and kicks being thrown around everywhere.
But when the eternal Holy War became the main war of the world, the warring species kept changing, and the way of fighting naturally evolved as well. The main fighting forces became infantry, spearmen, shield warriors, witches, curse warlocks, ballistas, and knights' charges. It was an era of cold weapons and magic.