The sword's name was not mentioned in The Silmarillion; it is only mentioned in the Lay of Leithian in The Lays of Beleriand. Beren possessed it when a lone outlaw on Dorthonian, but presumably lost it while battling the monsters of Ered Gorgoroth.
Dagmor was a Sindarin word for 'Slay Darkness'.
|Weapons of Middle-earth|
|Aeglos | Andúril | Anglachel | Anguirel | Angrist | Aranrúth | Belthronding | Dagmor | Dailir | Dramborleg | Durin's Axe | Glamdring | Grond | Grond (Warhammer) | Gúthwinë | Gurthang | Herugrim | Morgul-blade | Narsil | Orcrist | Red Arrow | Ringil | Sting|