>>2443718Fullers were put on swords to stiffen and lighten the blade. After military battles, the broken blades of the soldiers would be collected and repurposed into knives or short swords, and they would still have the fullers on them in this state. The fullers became "traditional" on knives because of this. They still actually serve their original purpose, but the stiffening and lightening needed for a 6" hunting knife is negligible.