A rare and immensely huge and big and gigantic gigaweapon (seriously, it's freaking big), the Rubion Sword was instrumental in the defeat of rather brief and very little-known Darkwardrobian Uprising by Zonard the Sunderer, the last of the Magic Sword Kings. After striking their leader Testiscisum down most mightily, Zonard proclaimed: "This is for better days. Let's go bowling." The Sword was then cast into Oblivion, or so it was thought...
It has been said that only the root of the Viagrium Shrub can make a man überhard enough to hold the mighty blade aloft, but it's actually optional.
This sword plays a critical role in the eponymous Book 3.