Since the dawn of man, rivalry, hate, ideology and competition have driven humans to combat each other. The earliest weapons in combat were probably sticks, rocks, pointed objects, or items that could be used to bludgeon one's opponent to death. Around the discovery of metallurgy and blacksmithing, a more lethal tool was devised: the sword.
Different kinds of swords developed around the world, but ultimately swords served two main combative functions: to slice through your opponent, either killing him or to remove an extremity; or to penetrate his body to pierce vital organs.
In ancient oriental cultures, swords (katanas or other similar small blades) were designed to be used in a swift swinging motion, preferring quick, light, sharp, blades that would cut through an opponent with minimal effort. This contrasted greatly with the swords developed by european feudal cultures, where swords were meant more for thrust and parry.
Wielding a sword correctly requires a great amount of skillsets: the ability to anticipate your opponents move; being able to deflect a strike; engaging and attacking while remaining agile. Swordplay is so technical in execution that fencing has become an olympic event.