Emperor's Sword (Weapon)
The Emperor's Sword is a giant flame-covered blade, that the Emperor created by using both his mastery of science and Warpcraft. Due to the nature of its creation, the Sword is anathema to the forces of Chaos and only the most powerful of Daemons can resist being destroyed by its mere touch. Indeed in the Emperor's skilled hands, the Sword destroyed thousands of daemonic creatures during the Great Crusade and Horus Heresy and even ended the life of the traitorous Warmaster Horus himself. However, the Emperor was nearly killed in that final battle with his Son and afterwards he was forced to be interred within the Golden Throne, to survive his mortal wounds. As for the the Sword itself, it was placed within its scabbard and rested upon one of the Emperor's knees, for ten millenia, until the beginning of the Thirteenth Black Crusade.
Abaddon the Despoiler's latest onslaught against the Imperium, saw the rebirth of the Primarch Guilliman and the Avenging Son was given his Father's weapon, to aid him in saving the Emperor's empire. It would go on to become the Primarch's primary weapon and despite no longer being wielded by the Emperor, the Sword still contains an essence of its creator's immense power. Due to this, Guilliman has noted that he feels the presence of his Father whenever he wields the Sword and thinks there are still secrets to the weapon that only the Emperor knows how to unleash.