The sword known as the Dornsblade or the Sword of Sebastus, is one of the most revered artefacts by those Space Marine Chapters who bear the genetic legacy of Primarch Rogal Dorn. The Champion of the Imperial Fists Successor Chapter who wins the centennial Feast of Blades has the honour of retaining the blade and the solemn duty of presenting it at the next Feast, the contest their Chapter will host, at most, one hundred Terran years later.
The simple, resplendent sword known as the Dornsblade can be traced back over ten millennia to the Great Scouring that followed the terrible galactic civil war known as the Horus Heresy. Rogal Dorn purposely broke the blade he had used aboard the Warmaster Horus' flagship, the Vengeful Spirit, when he failed to protect his beloved father the Emperor of Mankind from a mortal wounding at Horus' hands. His second sword, the weapon which the Imperial Fists and their Successor Chapters refer to as the Sword of Sebastus or the Dornsblade, emerged with the Primarch from the Battle of the Iron Cage on the world of Sebastus IV.
In Imperial custom, the greater the glory of the wielder of a weapon, the more extravagant the decoration of the weapon. Not so with the Dornsblade for it was a weapon that bespoke of spartan honesty and rang with history. It entranced the observer with the dull gleam of the honours eternally earned by it. It was rumoured to be unbreakable, a symbolic reminder of the unbreakable spirit of the Imperial Fists in the face of adversity, given form in the trials of the Iron Cage. It also represented the Imperial Fists Legion's continued unity despite the necessity of the Second Founding.
The Dornsblade was crafted from a single piece of high-grade Adamantium and remained completely unadorned. The cross guard, hilt and pommel were all bare metal, with the heavy blade counter-balanced by a solid pentagonal prism marked by angular edges and featureless faces. The hilt had been cross-hatched and scored to provide a grip, and the cross guard had been stamped with three simple numerals across its breadth: VII, denoting the original VII Legion of Astartes, the Imperial Fists. The blade was razored and featureless, bar its bronzed discolouration, which was believed to be the stain of the Traitor blood that had baptised the blade in Rogal Dorn’s hand during the Battle of the Iron Cage.
Following the Iron Cage, Rogal Dorn established the tradition known as the Feast of Blades - a centennial competition held between the Imperial Fists and their successors that involved ritual combat between select Imperial Fists Successor Chapter champions. This ritual combat was held within a ceremonial arena known as The Cage. The Cage is no dusty amphitheatre, for it is an architectural interpretation of the Iron Cage as far as accounts allow, but the layout is changed between and within each round – going so far as to shift the geometry of the field during battles.
Through the Feast of Blades, Dorn wanted to strengthen and temper the bonds of brotherhood through competition between the various Successor Chapters formed during the Second Founding when the Imperial Fists Legion was first split into separate Chapters. The sole remaining Champion who is blessed in the eyes of Dorn wins the Feast and is formally awarded the Dornsblade as his trophy and prize. The Chapter who won this honour was granted custodianship of the sacred blade and the solemn duty of presenting it at the next Feast that they would host one hundred Terran years later. The current holder of the blade is the Excoriators Chapter.
- Legion of the Damned (Novel) by Rob Sanders, pp. 55, 84