"Dai Hannya Nagamitsu" was the nickname of Ashikaga ********* (13th Ashikaga shogun)'s sword, Kokuho, which was passed as an honorific gift amongst the great rulers of feudal Japan, including Oda Nobunaga. The Dai Hannya is currently considered a national treasure of Japan, just like the uber-expensive Koryukagemitsu, the original Ghost in the Shell manga, and Yatta.
This pedantic little backstory, and the STR +3, makes the 300k I dropped on this puppy last week seem a bit more worthwhile... heh.