During The Cleansing , the Host of Valhalla  came to the Black City of the East and its formidable iron citadel. Upon its walls the host met city’s red witch and the terrible weapon she wielded, the Spear of Dawn. Unable to best her, the clans withdrew. But, The Cleansing would not be stayed nor slowed. The host continued west while this wart was besieged by a small contingent of young warriors.
A middling general among them, Warren Chiefsson, felt fortune’s wind blowing. He and his loyal companions followed it north into a fog shrouded land . Alighting on their ears, whispers of the Norns and their well, “Uroarbrunnr”. Certain to afford the answer to overcoming Dawn.
The companions encountered many perils and distractions. Stone pillars speaking babble . Ruins older than the gods . Wretched crones guarding gem stone springs . Tegel, haunt of blood lords and manor of madness . Always the fog, sapping their will. No Norns, no well.
The wind eventually led them to a cliff side cave near a great falls. Shouting in “How may I defeat Dawn” Warren received naught but his echo in reply. Again, he shouted to no effect. For the third try, the whole of the companions joined in. The cacophony of echoes enough to wake the King under the Mountain.
Roused by their passion The Oracle of Echo Cave  reverberated from the bowels of the earth, “Go quickly to Mentzar’s Tower of the Great Wall. Arrive nee dawn and find what you seek.” Warren sped away. Abandoning his companions to die battling the Echo Cave Guardian that was also roused.
As night beat down the day it was clear Warren would fail and all his efforts were for naught. In the pale glow of Full Nidavellir  Warren demanded the gods favor. In response an old man appeared. Warren assumed this was sly Odin  in disguise but was in fact Loki . This bearded stranger offered assistance that Warren accepted without thought as to price. Smiling to himself, the old man limped away into the foggy night, croaking out. “Look to the skies, look to the skies.”
A tremendous wind nearly knocked Warren down. When he recovered the great Eagle perched over him. It spake, “I am Mother , climb into my talon.” And thus Warren was carried away to the East and the Tower of Mentzar. Where the first rays of the day illuminated a passage leading below. Warren never spoke of what perils he faced beneath that tower. Only that he pulled a mighty sword, Dawn Breaker, from the maw of a terrible wolf.
Seeing Dawn Breaker, his brethren were convinced to follow Warren in a new assault of the black city. Sundering the Spear of Dawn and slaying the enemies lord in a single blow. The black cowards routed and were cut down. Their vile city pillaged and put to the torch.
During the ensuing victory feast, Warren and his brothers bickered over division of spoils. They wishing to follow tradition, he claiming a chief’s share. Some say an old, bearded man goaded Warren. Others that Warren simply achieved success beyond his wisdom. Regardless why, Warren drew Dawn Breaker and cowardly slew his youngest and weakest brother.
Thereafter the Kin-Slayer hunted the rest of his brothers killing many of his clan. Before the Troll Bloods  trapped the foolish child. He and those who followed him were cursed, prevented from returning to Hyboria , and exiled from Valhalla .
Thus ends the Saga of Dawn Breaker
Lifting the Kin-Slayer Curse¶
As related by Arden Brokmunsen, Skald of the Rus.
Dawn Breaker in your language would be daylight. It will be strongest just after dawn and weakest at dusk. In the Hyborian way of thinking, dusk is what “breaks” daylight.
The sword and Kin-slayer are linked by curse. Breaking this link is key to breaking the curse. Defeating Kin-slayer and taking the Dawn Breaker is not enough. He will always seek to claim that which has cursed him.
I am curious why, once freed from his cairn, The Kin-Slayer has not ventured further afield than the barrowmounds. Carrying Dawn Breaker out of Kin-slayer’s reach won’t break the curse but will certainly weaken him and allow you use of the sword. Your true goal no doubt.
Destroying Dawn Breaker would work. As, might returning it to where it was found. A risky approach would be getting Dawn Breaker to abandon the Kin-slayer for a new wielder. Likely requiring the slaying of relation and adoption of curse. But, in your dishonorable culture kin-slaying is less crime than looking askance at a lord.