Rhunön was the elven Smith who made every Rider's sword during the Dragon Rider era, a devastatingly beautiful and powerful weapon that would match the colour of the Dragon of the Rider wielding the weapon. She later vowed to never make another sword again after Galbatorix gained power, destroying all the Riders with the blade she had made for him. Even after Brom begged her to replace the sword he lost in the Dragon War, Rhunön kept her promise. She was credited as the "most skilled smith in the world", even surpassing the dwarves.
The named swords forged by Rhunön were
- Arvindr (for an unknown Rider)
- Brisingr (for Eragon)
- Naegling (for Oromis)
- Támerlein (for Arva, reworked for Arya)
- Undbitr (for Brom)
- Zar'roc (for Morzan, later Eragon, later Murtagh)
- Islingr (for Vrael, renamed Vrangr after Galbatorix came into possession of it)
Rhunön was very introverted and very rarely left her forge: when she did, it usually required quite a bit of wheedling from Arya. The only time she really left when Eragon was in Ellesméra was the eve of the Blood-Oath Celebration. Eragon also noticed that she was the only elf that looked even the slightest bit old: this could possibly suggest a look of weariness or sadness (perhaps from sorrow or guilt due to the fate of her creations), or could imply that, as other elves used magic to manipulate their features, she may have chosen to appear old for some unknown reason (possibly because she doesn't like using magic, she allows herself to appear old). Or because she is the oldest of her kind still alive. It could also be due to the fact that she can remember how the elves were before they bonded with the dragons and thus could have been old before the elves became immortal and merely never took the time to change her appearance. In her mind, making herself beautiful would probably be a waste of time and energy, for it would not serve a purpose. Rhunön was entirely devoted to her craft, rarely using magic in the process. At one point during Eldest, Eragon notices that she has welded shut each individual link in a shirt of mail she was working on and questions why Rhunön doesnt simply use magic to save herself the time and effort. The master forger responds with passion, informing him, "When you can have anything you want by uttering a few words, the goal matters not, only the journey to it."
Rhunön is possibly one of the oldest elves in existence. While the exact number of years she possesses is unknown, she was old long before the dawn of the Riders. In Eldest, it's noted that she remembers a time before the pact between elves and dragons was sung into being. This puts Rhunön at at least a thousand years old.
She first learned her craft from Fûthark, a legendary grimstborith of Dûrgrimst Ingeitum clan. She can apparently converse in dwarvish and does when she greets Orik at the Blood-Oath Celebration, inviting him to visit her forge.
When Eragon asks for a new sword (after losing Zar'roc to Murtagh), Rhunön is intrigued by the idea of creating the blade that would end Galbatorix's life, but has no "brightsteel", the metal used to make Rider swords. Eragon finds some underneath the Menoa Tree, to which Rhunön said that the amount Eragon found could make several swords. She made a sword matching Saphira's color which Eragon christened "Brisingr". Rhunön avoided breaking her oath to never create another "instrument of death" by guiding Eragon's mind directly, using him to create it, thus making the craft different enough in her mind to avoid the oath, as she didn't make it with her own hands. When Eragon named his sword, he was surprised that it burst into flames when he spoke it's name. He had Rhunön try it but the sword remained normal except for a small shiver that seemed to run it's length. She guessed that Eragon may have discovered the True Name of the sword, or perhaps the magical flames came from him forging the weapon. Rhunön said Brisingr is the finest Rider sword she had forged.
After the green egg hatched for Arya, Rhunön begrudgingly reworked the sword Támerlein to more fit her .