Belthronding : I have never seen a translation of the name.
No name, or year, appear as the crafter of Belthronding, thus I expect Beleg had made it.
The great bow of Beleg Cúthalion made of black yew-wood. This bow, hard horn pointed and stringed with bears sinews, so strong and hard that no man or elf had the strength to bend it save Beleg who, apparently as it is told so in the book The Lays of Beleriand, had some magic to help him. Belthronding and the beloved dart Dailir was Beleg Cúthalion`s primary weapon.
In the years below Belthronding was, or might be expected, used and carried by Beleg.
F.A.458. Beleg brought Elves and strength into Brethil and aided Haleth and the people of Brethil in war.
F.A.466. Beleg, Thingol, Húan, Mablung and Beren hunted Carcharoth.
F.A.481. Beleg became friend with Turin and they hunted, battled and secured the marches of Doriath.
F.A.487. Beleg was captured by Turin but released and they renewed their friendship.
F.A.489. Beleg and Turin fought at Amon Rûdh.
F.A.490. Belthronding was buried with Beleg in Taur-nu-Fuin by Gwindor