- Shireen Baratheon: "Ser Byron Swann wanted to kill the dragon Vhagar. He polished his shield for a week so that it was like a mirror. And he crouched behind it and crept forward, hoping the dragon would only see its own reflection."
- Davos Seaworth: "But the dragon only saw a dumb man holding a mirrored shield."
- Shireen Baratheon: "And burnt him to a crisp."
- Davos Seaworth: "Thus ending the dragonslaying career of Ser Byron Swann."
- — Davos and Shireen share a laugh.[src]
During the civil war, Ser Byron attempted to slay a dragon by polishing his shield for a week too make it as reflective as possible. Hoping to seek up on the dragon, Ser Byron was fatally mistaken and burnt to death by the dragon. His death was written about in The Dance of the Dragons, A True Telling by Grand Maester Munkun.
In the books
In the A Song of Ice and Fire novels when Tyrion Lannister is in Pentos, he briefly assumes the false identity of Hugor Hill is asked to prove he is truly a Westerosi by naming a knight tried to killed a dragon during the Dance of Dragons imitating a famous legend from the Age of Heroes.
No only does Tyrion know it was Ser Byron Swann, but also notes that Grand Maester Munkun erred in his book - Byron didn't try to kill Vhagar, he tried to kill Rhaenyra Targaryen's dragon Syrax. As Tyrion explains, Ser Byron Swann was the son of a marcher lord, who was sworn to House Baratheon, who declared for King Aegon II Targaryen. Moreover, Vhagar was ridden by Prince Aemond Targaryen, King Aegon II's brother - so it really wouldn't make sense for Bryon to try to kill Vhagar. Some time ago, Tyrion noticed the discrepancy in the course of his own studies, and even researched it further by obtaining a letter written by by Ser Byron Swann's squire - who witnessed Ser Bryon's death - to the squire's daughter, and in the letter it was stated that Syrax killed him.