A long time ago the dragon Ostreverg ravaged and plundered the sacred Temple of Freya on the Skellige Islands. Three brothers, the sons of a jarl, vowed to recover the goddess' relics. The priestesses granted them diagrams of three ancient suits of armor so that they would be able to face the dragon's formidable fangs and devastating breath of fire. The smith Sigurd Ironlord forged the sacred armor for them.
[…] The second oldest brother ultimately slew the dragon. He deemed it unjust that his elder brother, who had proved himself a coward and fled the beast, would inherit their father's title and lands. Thus, he pursued his brother to strip him of his birthright. Since he could not force the Oathbreaker to renounce his claim, he killed his brother with his sacred blade. This deed brought a curse down upon him, and he became known as the Kinslayer. As the anathema was worded, he would live as long as he wore his complete outfit.
[…] The Kinslayer traveled to Loc Muinne, for a sorcerer who claimed he could lift the curse had summoned him there. In fact, the mage had lied - he merely wished to unlock the secrets of the wondrous armor. He asked the Kinslayer for his sword, and when the brother parted with his blade, the prophecy was fulfilled. The diagrams of the Kinslayer's Outfit remain hidden amidst the ruins of Loc Muinne to this day.