The tuatha dé came to Ireland and fought the Fir Bolg for rule of the land. Although wielding the powerful sword of light, Claímh Solais, during the height of battle, Nuada sustained a severing of his arm by the Fir Bolg’s champion, Sreng. The Dagda (the channelers and gods of the Tuatha) swarm to his side, with their chief Dagda sustaining Nuada’s life and 50 of his best warriors seeing him safely from the field. Although the arm could not be saved in time, Nuada recovered and challenged Sreng to a rematch. He would accept the duel only with his combatant agreed to tie down one arm to make the opposition fair. When Sreng declined, knowing that his only chance for victory during one on one combat was to face the mighty Tuatha king while disadvantaged, Sreng forfeit the duel. Nuada claimed victory and the natives were cornered into a small portion of the island.
However, tradition stated that in order for Nuada to rule, he must be physically whole. There was only one god across the sea capable of restoring the lost arm, so in anticipation of the journey to seek the healer, King Nuada named a regent to rule in his place. Although beautiful and powerful, King Regent Bres was a shocking choice for Nuada to select. Bres was of an angry and blunt race of people feared more than beloved, but Nuada worried that anyone less than the might of Bres may not withhold the Fir Bolg as they sought revenge. He left the island to King Regent Bres’ hands, and journeyed across the sea to be made whole.
To the (now lost) isles of the Tuatha, Nuada returned. He found a man by the name of Dian Cecht, whose work was renown, but came at a steep price. It was said he could heal any manner of ill, from tumors that grow to that which the animals tear, which fire burns, and iron severs. The god of healing and his wright, a god of famous metalworking, would together fashion a new arm of shining silver, but the cost of which was to come from Nuada’s Sword of Light itself. To do so required the ter’angreal sword to be melted, as only the purest of metals could form an arm of strength and never-wear. Nuada’s body would long decay but the arm would survive the ages. The sword of light was a famous treasure, capable of dissolving or deflecting the gods’ magic depending on the need of its wielder. Knowing he would never return to his place as king while handicapped, he reluctantly sacrificed the sword for the metalworkings, and the wright and healer upheld their end of the bargain.
The magic of the sword, however, was unexpected. It resisted the magic of Dian Cecht as it resisted all magics, and delivered a destructive blow upon its disturbance. Nuada escaped without his newly working arm, but to his sorrow, left behind the remains of his sword as well. He fled the anger of Dian Cecht, who himself was injured in the explosion, but ironically, unable to heal himself.
Nuada eventually took refuge with another healer, that of the son of Dian Cecht, a young man named Miach. Stifled and abused by Dian Cecht, Miach journeyed most of his adult life seeking training by other gods of healing across the world. What he offered to Nuada was a chance to defeat his father in exchange for replacing the arm previously promised. The deal was struck and the genius of Miach was revealed. From the buds of others taking their final breaths, he wove an arm of flesh and blood and reattached it to Nuada’s shoulder. With sheer gratitude, Nuada himself brought Miach back to Dian Cecht and together they faced the god and his wrights.
Both Miach and Dian Cecht died in battle that day, but the workings of the sword of light were recovered. After 7 years, Nuada returned to his kingdom with a new arm of flesh and blood, and delivered the sword of light to be reformed.
Upon his return to Ireland, he found the king regent a tyrant in his stead. Bres was on the verge of war with not only the Fir Bolg but also the giants of his own race, the Formians. Nuada rallied, drawing new champions to his court, including the vigorous and heroic Lugh, unseated Bres and calmed the land. The remainder of Nuada’s rule was one of peace until Bres returned 20 years later with fresh forces to once again engage Nuada. The sword of light flashed in battle as powerful as ever, but Nuada was killed by the evil god Balor, whose strange green flows were the only ones unable to be deflected by the sword of light.
Lugh himself avenged Nuada by killing Balor before beginning his rule.
The sword of Light of Nuada is a weapon that can either dissolve or deflect weaves of the one power depending on the need of its wielder. The only exception being that of balefire or its derivatives (such as the Flame of Tar Valon), a greenish twist of which was used by Balor, and the sword could not deflect it, killing Nuada.