The Honjo Masamune is a ritually forged, ancient Japanese katana with a blade so perfectly balanced and aligned that it splits light, rendering its wielder invisible. Also it's literally the sharpest sword ever made.
The sword was forged by Gorō Nyūdō Masamune, and is said to have kept the ruling shogunate in power for hundreds of years by making them invincible in battle (however, see for reference the continuity issues noted below). Artie claims that the beauty of the sword rests not in its appearance, but in the way was originally forged. He waxes poetic when he says it was a "hammered and folded blade, [with] millions of layers of steel [and] a carbon content that's right off the charts. And each layer only atoms – atoms – thick."
It was lost in history and the incomplete blade was rediscovered at a dig site in Okinawa, Japan in 2009. The Japanese government was going to offer the sword to the American government in a ceremony until it was stolen from the embassy where it was being housed before the presentation. The sword was being stored without a piece critical to its construction: the tsuba, a disk-shaped guard between the blade and the handle, was not found in the Okinawa dig site, but was known to have been in the possession of an antiques dealer in Tokyo in the 1920s. It was eventually presented by the Japanese government to President Woodrow Wilson in the 1920s as a symbol of peace.
The curator of the modern Woodrow Wilson Museum of Peace recognized the sword that was being presented to the American government as the mate to the tsuba in the museum's collection and offered to reunite the two pieces at the gifting ceremony that was going to take place. The tsuba was brought to the Secret Service building in Washington D.C. for safe keeping until the ceremony. When implosions struck the embassy building and the ceremony was cancelled, the tsuba was scheduled for return to the museum before the pieces could be reunited.
The tsuba was eventually recovered and reunited with the blade at hangar CA-5A in Washington Dulles International Airport in 2009 and is now stored in an acrylic tube with the warning "DO NOT APPLY TSUBA ONTO SWORD" on its label and is next to a clock of unknown purpose.
How it WorksEdit
The blade is so perfectly forged that its balanced and alignment make it possible for light to split in its path and go around the person holding it, rendering them invisible if the blade is held point up and directly in front of them. It is incapable of causing invisibility if the sword and the tsuba are apart from each other.
Artie claims that the sword is 800 years old, specifically correcting a rounded 500-year-age voiced by Pete. But when Pete calls Leena for hints on how to find the sword's missing tsuba, Leena states that Artie spoke of the sword being from the Edo period of Japanese history (the correct period, historically, of the actual Honjo Masamune). The Edo period, however, spanned from 1603 to 1868 CE, which would make the sword between 140 and 400 years old. If the sword were 800 years old, it would be from the earliest years of the Kamakura period, which spanned from 1185 to 1333 CE.
Real World ConnectionsEdit
The idea of bending light was originally proposed by Sir Isaac Newton in 1704 at the end of his treatise on the nature of optics. Little was done with the idea until it was revived in 1911 by Albert Einstein when he wrote "On the Influence of Gravitation on the Propagation of Light" and which he continued to refine and correct into more a elegant theory through 1915 when he completed his general theory of relativity.