Ice was the ancestral Valyrian-steel greatsword of House Stark of Winterfell, borne by the Lords of Winterfell for four hundred years before the Conquest. The blade was so wide that two men could have laid head to head along its length, and Lord Eddard carried it himself to every execution held in the godswood.
After Lord Eddard's death on the steps of Baelor's Sept in 299 AC, his sword was taken to King's Landing and given over to Tywin Lannister, who broke it down and bade his armourers reforge it into two new blades. The smaller, paler sword was given to King Joffrey, who named it Widow's Wail; the larger went, by Tywin's wish, to Jaime, and Jaime in turn gave it to Brienne of Tarth and bade her find Sansa Stark with it. Brienne calls her sword Oathkeeper.
Of the blade Lord Rickard and Lord Eddard carried, nothing remains.