Do we know <PERSON>'s real name?
During the events of The Hobbit, after dealing with the trolls, the <PERSON> and co. find three magic weapons in the troll's lair:
... among them were several swords of various makes, shapes, and sizes. Two caught their eyes particularly, because of their beautiful scabbards and jeweled hilts.
<PERSON> and <PERSON> each took one of these; and <PERSON> took a knife in a leather sheath. It would have made only a tiny pocket-knife for a troll, but it was as good as a short sword for the hobbit.
"These look like good blades," said the wizard, half drawing them and looking at them curiously. "They were not made by any troll, not by any smith among mend in these parts and days; but when we can read the runes on them, we shall know more about them."
Chapter 2, Roast Mutton, pp. 55-56
Two of the swords found have names, Orcrist (which translates to Goblin-cleaver) and Glamdring (which translates to Foehammer), as <PERSON> tells us in the next chapter:
<PERSON> knew all about runes of every kind. That day he looked at the swords they had brought from the troll's lair, and he said: "These are not troll-make. They are old swords, very old swords of the High Elves of the West, my kin. They were made in Gondolin for the Goblin-wars. They must have come from a dragon's hoard or goblin plunder, for dragons and goblins destroyed that city many ages ago. This, <PERSON>, the runes name Orcrist, the Goblin-cleaver in the ancient tongue of Gondolin; it was a famous blade. This, <PERSON>, was Glamdring, Foe-hammer that the king of Gondolin once wore. Keep them well!"
Chapter 3, A Short Rest, p. 67
However, <PERSON> does not take a look at <PERSON>'s blade, and it is not mentioned in the above meeting with <PERSON>. 381
The name "<PERSON>" is one that <PERSON> himself gives it after fighting off a giant spider of Mirkwood, inspired by his victory over it:
He beat the creature off with his hands–it was trying to poison him to keep him quiet, as small spiders do to flies–until he remembered his sword and drew it out. Then the spider jumped back, and he had time to cut his legs loose. After that it was his turn to attack. The spider evidently was not used to things that carried such stings at their sides, or it would have hurried away quicker. <PERSON> came at it before it could disappear and stuck it with his sword right in the eyes. Then it went mad and leaped and danced and flung out its legs in horrible jerks, until he killed it with another stroke; and then he fell down and remembered nothing more for a long while.
There was the usual dim grey light of the forest-day about him when he came to his senses. The spider lay dead beside him, and his sword-blade was stained black. Somehow the killing of the giant spider, all along by himself in the dark without the help of the wizard or the dwarves or of anyone else, made a great difference to Mr. <PERSON>. He felt like a different person, and much fiercer and bolder in spite of an empty stomach, as he wiped his sword on the grass and put it back into its sheath.
"I will give you a name," he said to it, "and I shall call you <PERSON>."
Chapter 8, Flies and Spiders, pp. 198-199
<PERSON> shows up again in The Lord of the Rings, where <PERSON> gives it to <PERSON>, but <PERSON> is still referring to it as "<PERSON>". Do we ever learn its real name (whether its elvish name or its translation), either in The Hobbit (unlikely), The Lord of the Rings (possibly) or any of <PERSON>'s other works (e.g. The Silmarillion, etc)?
All the page numbers are according to my copy, which is the <PERSON> illustrated edition. I'm not sure if the page numbers are the same in every edition, and if not, whether it's useful to include page numbers. These page numbers can be removed if it doesn't add anything to the post. 381