Sword of Nalin
From Adventures, Etc
The Sword of Nalin is both a series, a set of books set on the world Daea, and a mythical object from within those worlds.
The Series
Thus far the series only features the published book The Five.
Two sequels are in the works, awaiting editing and covers.
The Sword
In the story, the sword is supposedly wielded by Nalin, the King Arthur historical figure on Daea.