it's actually about ethics in blacksmithing

Swords are what drove culture in the medieval ages in Europe and during Japan's samurai days. It was an interesting development. During Roman times, the Romans used a strong shield and a very short sword, more often referred to as a gladius. Their common foes, the Gauls and Germans, used large two-handed swords. Despite being victorious over their foes, proving that a shield, short sword, and discipline are superior, why did the world start shifting over to heavier swords and heavier armor?