As Armor Improved, Swords Became Less Effective

As armor improved, and more and more foot soldiers as well as knights were equipped with it, the sword became less and less effective as a weapon. To a degree this was acceptable, because in many medieval fights between knights the object was not to kill your opponent, but rather to render him helpless so that he could be captured. After all, when ransomed he was worth a great deal of money! Another very valid reason for this “compassion” was that if you started killing others of the aristocracy, you might very well be killed yourself!

— The Book of Swords, p. 65