Dawnbreaker is a Daedric artifact created by the Daedric Prince Meridia. It was forged "in a holy light that breaks upon" the Prince's foes. In appearance it is an ebony longsword containing a distinctive light emitting crystal in its cross-guard known as the Dawnstar Gem. It was created with the intention of "burning away corruption and false life". As such, it is particularly effective against Meridia's "foes": this primarily applies to the undead, although its powers can also be used on Daedra and werewolves.
Dawnbreaker is known to deal magical or fire damage to those it strikes, along with additional damage to the Prince's foes, sometimes knocking them to the ground. When an undead creature is killed by the weapon, there is a chance that it will cause a fiery explosion, burning all other undead in its radius and causing them to flee. This explosion can prove dangerous if the wielder is also undead, such as a vampire. Those who possess Dawnbreaker are sometimes known to do more damage with mundane weapons.
During the time of the Planemeld, the Fighters Guild was commissioned to destroy Dark Anchors sent to Tamriel by Molag Bal. The highest ranking members were given the power to summon Dawnbreaker in the midst of battle to aid them in fulfilling this contract.
After his supposed death and reemergence in the Colored Rooms, Darien Gautier was revealed to be the champion and the Vessel of Meridia and was given Dawnbreaker for his fight against the Court of Bedlam during the cult's assault on Summerset Isle circa 2E 582. The sword soon fell out of his possession during their quest to reclaim the Heart of Transparent Law alongside the Psijic Order, as it was stolen by Nocturnal and altered by her power. The Goddess of Shadows bequeathed the sword to her own champion, Earl Tundilwen, who referred to the new sword as Duskbringer..
Tundilwen was seen wielding Duskbringer in the battle within the Crystal Tower, where she was slain by Darien Gautier and the Vestige. As the last Light of Meridia, Darien then sacrificed himself to remove Nocturnal's corruption and restore Dawnbreaker. The Vestige was able to use the Dawnbreaker to ascend to the top of the Tower and hold back Nocturnal's forces long enough to plunge the sword into Transparent Law in order to repair and cleanse it of Nocturnal's influence and saving all reality.
Sometime after the end of the Great War, around 4E 180, the former member of the Blades, the Warrior, came across Dawnbreaker in their journey. The method of acquisition of the sword is conflicted, however. Some claim that it was obtained from the plane of Oblivion known as The Abyss, while others believe it was looted from a chest obtained from a conflicted location.
At some point, Dawnbreaker was brought to Meridia's temple at Mount Kilkreath in Skyrim. In 4E 201, a Breton necromancer named Malkoran defiled the temple, and began trapping the souls of dead soldiers in the ongoing Stormcloak Rebellion. He used Dawnbreaker's power to fuel his profane magic, which greatly offended the Prince. In response, Meridia summoned the Last Dragonborn to Mount Kilkreath to cleanse the temple ruins and claim Dawnbreaker.