Celeg Aithorn

Celeg Aithorn was a mythical Sword of the First Age. Beleg Cúthalion mentioned it in his 'whetting spell' while sharpening his sword to cut the bonds of Túrin Turambar after he and Gwindor had rescued him from the Orcs. Beleg calls it "Celeg Aithorn who shall cleave the world". The Name Caleg aithorn might be translated as Swift Spearpoint-Tree or Swift good Eagle. The prophecy that it shall once cleave the world is believed to be a hint towards the Dagor Dagorath. It has been suggested that Celeg Aithorn refers to lightning, the Sword of Manwe.

Angband
In the Angband roguelike Celeg Aithorn is considered a magic Mithril Longsword.