Glamdring
Description
Glamdring, the Foe-hammer, was the legendary sword of Gondolin used by the wizard Gandalf through the events of both The Hobbit and The Lord of the Rings. One of the most famous weapons in the long history of Middle-earth, Glamdring was witness to many of the major events in both the First and Third Ages, and saw more than it's fair share of battle in that time.
Originally the sword of Turgon, the High-King of the Noldor and King of Gondolin, Glamdring was forged in the First Age at the height of that ancient city's prestige, and like Orcrist and Sting, produced a cold light when orcs were close. Turgon likely used it during both the Nirnaeth Arnoediad and the Fall of Gondolin, the latter of which saw the King's death, and the sword's disappearance for nigh on 6,000 years. Even still, orcs and goblins were fearful of it's name, and simply called it "Beater".
Miraculously, Glamdring survived both the War of Wrath and the Sinking of Beleriand, and by T.A. 2941, it, along with Orcrist and Sting, came into the possession of the hoard of three stone-trolls in the Trollshaws. How they came into the possession of Tom, Bert, and William is unknown, though it's possible it was simply the latest in a long line of plunderings from different owners. The three blades were saved by Gandalf and Thorin's Company, and Gandalf would go on to wield it throughout the last decades of the Third Age, especially during the most critical moments of the War of the Ring.