The Ancestor’s Spear has the special ability to consume the madra of sacred artists stabbed by the weapon, funneling their madra into the core of the wielder. While not a perfect weapon, it remains an incredibly powerful one, like all weapons found in the Labyrinth. It was created via advanced soulsmithing and employs hunger madra. It supposedly belonged to the Jai Clan of the Blackflame Empire. It has been locked in the Labyrinth for centuries, out of reach until now. . . When the underground maze uprose suddenly, becoming the Transcendent Ruins.
The spear is first mentioned in Soulsmith. It is the prize of the Transcendent Ruins, an enormous labyrinthine pyramid that rose from the ground a few short days before our protagonists reach it. The labyrinth attracts all the dreadbeasts for miles.
Upon reaching the ruins, Lindon and Yerin learn that five factions are hunting the spear within the ruins: Sandviper Gokren and his son Kral leading the Sandviper Sect, working with Jai Long of the Jai clan, the Purelake School, and the Fisher clan, with soulsmith Fisher Gesha, all of whom are competing to get the spear. This is the Five Faction Alliance, although we never discover the fifth group.
After several different confrontations and a training montage the spear is found by Yerin and Lindon, guided by their newly minted mentor Eithan Arelius. However, the Sandvipers find them while they are looting the ruins and in the confrontation Sandviper Kral is killed by Lindon. Kral is Sandviper Gokren’s heir and Jai Long’s friend. Before Jai Long can take his revenge, Eithan intercedes, saving Lindon but promising Jai Long that Lindon will be prepared to duel him in one year. Eithan also gives Jai Long the Ancestor’s Spear.
Jump to book 3, Blackflame: Over the course of that year, Jai Long uses that spear to wreak vengeance against his Jai Clan, because in childhood they abandoned him and his injured little sister, Jai Chen. The spear helps speed his advancement to Truegold but eventually, when confronted by Patriarch and Underlord Jai Daishou, he gives up his rebellion and pledges loyalty in exchange for his kidnapped sister’s life. Jai Daishou then attacks Eithan who "kills" him and takes the spear. But Daishou doesn’t die.
Jai Daishou then goes to the western labyrinth and risks the threat of the Dreadgods and the wrath of the emperor by entering the Lord level area. There he finds a replacement for the spear, however, it is broken. He believes that a soulsmith can repair the cracked one. He also takes the dangerous Archstone to use against his hated enemy, Eithan Arelius.
The next time we see the Ancestor’s Spear is during Jai Long’s duel with Lindon, in book 4 Skysworn. For the first half of the fight he uses a regular spear before pulling the Ancestor’s Spear from his soul space. Jai Long tends to dominate the fight but Lindon is actually able to break the spear during the battle. Teenage sister Jai Chen picks up the broken spear and uses it to kill Jai Daishou, who is wielding the stolen Archstone. Captain Naru Gwei of the Skysworn, adjudicating the duel, takes the dangerous Archstone to his emperor, but the broken spearhead is overlooked, and stealthily snatched up by Eithan.
Lindon lost his arm during the duel and needs Fisher Gesha to help him soulsmith a replacement prosthetic. He actually uses the binding found in the broken Ancestor’s Spearhead. This is what makes his arm a hunger madra weapon.