- This article is about the lore of the weapon. For the quest, see . For the achievement, see .
- For the quest item, see . For the quest object, see Glowing Runeblade.
Before his disappearance, the Primus hid an unfinished blade with no hilt inside a standing rock in a lava pool in the House of the Chosen, along with a message stating that the Shadowlands would fall into darkness, frayed bonds had to be restored, and "the key [would] honor the worthy". He etched five runes into the blade corresponding to five runes covering the sanctum door into the Seat of the Primus, each representing one of the traits of the ideal Maldraxxi soldier: ambition, might, guile, insight, and the relentless pursuit of victory. As a test of the potential forger's skill, he also enchanted the blade by trapping a number of souls inside it.
Reaching the standing stone became a trial of endurance for the most renowned members of the House of the Chosen. However, although many souls succeeded in reaching it, none discovered what the rock contained until the Maw Walker, whose touch activated the Primus' message and revealed the blade. Baroness Draka sent the Maw Walker to the Primus' apprentice, Bonesmith Heirmir, who decided the object had to be turned into a proper weapon. With hide scraps from the land itself as raw materials and the anima-infused bones of Marrowjaw as the hilt, Heirmir forged the unfinished blade into a proper sword while the Maw Walker held off the soul guardians that emerged from it. As soon as the weapon was finished, Heirmir was knocked away by a blast of energy and commented that the Maw Walker was evidently the only one meant to wield it. When the hero took up the weapon, they activated its first rune, the Rune of Ambition.
Margrave Krexus deduced that the sword's runes were the same as the ones on the Seat of the Primus—which had been sealed since the Primus' disappearance—and sent the Maw Walker there with Baroness Draka and Baron Vyraz to see what would happen. When the Maw Walker held up the blade to the entrance, the Rune of Ambition transferred its power to the sanctum door. However, Vyraz insisted that accessing the Seat would do them no good if the Chosen fell in battle against the traitorous House of Constructs and House of Rituals. The Maw Walker was tasked with recruiting new allies to the war, but these efforts awakened three more of the blade's runes in the process:
- The Rune of Guile was empowered after the hero and Baroness Vashj used deception to lure the lich Mor'Bitan into the open and kill him.
- The Rune of Insight was awakened after the hero helped briefly restore the sanity of Plague Deviser Marileth and Margrave Stradama with a special potion.
- The Rune of Might was empowered after the hero displayed their power by using the Soulfused Construct to wreak havoc on the House of Constructs.
It was eventually revealed that Vyraz was in league with the House of Constructs and House of Rituals and had betrayed and killed Margrave Krexus. When the Maw Walker confronted Vyraz alongside Alexandros Mograine, they awakened the fifth and final rune, the Rune of the Relentless. When Vyraz saw that the runeblade had been completed, he declared that he would take it from the hero's corpse. However, the duel was interrupted when Draka arrived to bring the Maw Walker and Alexandros back to the Seat to defend it from an assault by Vyraz's forces. While the Maw Walker's allies held the line, the hero used their runeblade to open the door into the Seat and cause the Primus' power to cut a swath of destruction through the traitorous Maldraxxi, forcing them to retreat. When the hero entered the Seat and approached a stone altar, the runeblade began glowing brighter. The Maw Walker planted the blade in the altar, triggering a dire warning from the Primus: the Eternal Ones had to stand together once more to prevent the Jailer from escaping his imprisonment in the Maw. Draka concluded that the message must have been put there to await one who proved worthy of hearing it. The Maw Walker subsequently returned to Oribos to deliver the warning to the other Eternal Ones.
Maw Walkers who returned to Maldraxxus to join the Necrolord Covenant brandished the Blade of the Primus as part of the ceremony to join the covenant and receive the power of the Primus. Later, during the Necrolord and kyrian assault on the House of Constructs, Alexandros devised a plan to deal with Margrave Gharmal's Bilebloat Juggernauts by using the runeblade. First, he instructed Maw Walkers to kill Gharmal's empowered forces in the Stitchyard and absorb their essence into the blade. Then, he and the heroes mounted his deathroc Marrow, headed into the sky above the Stitchyard, and unleashed the blade's power in a flurry of necrotic bolts that destroyed the juggernauts.
As a quest objective
- is looted for .
- Glowing Runeblade has to be interacted with in .