Things of Middle-earth
Meaning: King's Ire
The sword made by Dwarves for Elu Thingol, King of Doriath; later an heirloom of the Kings of Númenor:
A golden crown [the Dwarf-folk] made for [Thingol 1]..., and a helm too...; and a sword of dwarven steel brought from afar was hilted with bright gold and damascened 2 in gold and silver with strange figurings wherein was pictured clear the wolf-hunt of [Carcharoth 1] Knife-fang, father of wolves. That was a more wonderful sword than any [he] had seen before....
The Book of Lost Tales 2, HoME Vol 2, Ch 4, The Nauglafring
From Thingol, the sword descended to his granddaughter Elwing and then to her son, Elros Tar-Minyatur; it then became the traditional sword of the Kings of Númenor.
The King and most of the great chieftains possessed swords as heirlooms of their fathers....
Unfinished Tales, Part 2, Ch 1, Description of the Island of Númenor
Ibid., Note 2
We know that Aranrúth did not survive past the Downfall of Númenor:
Although Tolkien does not say, it is quite possible that Aranrúth was carried by Ar-Pharazôn, the last King of Númenor, on his ill-fated invasion of Valinor and lost with him:
The Silmarillion, Akallabêth
ar(a)- 'high, noble, royal' appears in a great many names, as Aradan, Aredhel, Argonath, Arnor, etc.; extended stem arat- appearing in Aratar, and in arato 'champion, eminent man', e.g. Angrod from Angaráto and Finrod from Findaráto; also aran 'king' in Aranrúth. Ereinion 'scion of kings' (name of Gil-galad) has the plural of aran; cf. Fornost Erain 'Norbury of the Kings' in Arnor. The prefix Ar- of the Adûnaic names of the Kings of Númenor was derived from this....
ruth 'anger' in Aranrúth.
The Silmarillion, Appendix: Elements in Quenya and Sindarin Names
1 This text is from one of Tolkien's early drafts. For the sake of clarity, earlier versions of proper names used by Tolkien in this draft have been replaced with the versions in use in the canon sources: Thingol for Tinwelint, and Carcharoth for Karkaras. All substitutions are marked with brackets.
2 ... 'damascened', ornamentally inlaid with designs in gold and silver.
The Book of Lost Tales 2, HoME Vol 2, Ch 4, The Nauglafring: Notes and Commentary, Note 7
Elena Tiriel 4Feb10