Who was arthur's second sword given to him by?
"And Arinbjorn gave Egil the sword called Dragvandill. This had been given to Arinbjorn by Thorolf Skallagrimsson; but before that Skallagrim had received it from Thorolf his brother; but to Thorolf the sword was given by Grim Shaggy-skin, son of Kettle Hæing. Kettle Hæing had owned the sword and used it in his single combats, and no sword was there more biting." TRANSLATED FROM THE ICELANDIC, BY REV. W. C. GREEN
Morzan, the rider, had the sword Zar'rok formed from the elven master forger, and was given to Morzan just before he betrayed the riders. Then, when Brom killed him, he stole his sword which was supposed to be given to Murtagh, but then gave it to Eragon because he knew that he has more supposed to have it than Brom.
The island of Avalon, and Arthur's scabbard are considered supernatural. Arthur's scabbard for excalibur is supernatural because as long as he wears it, he cannot die of his wounds. The island of Avalon is supernatural because it is a hidden land that humans generally can not go to. The catching of King Arthurs sword.