Blackfire was Valyrian sword that was brought to Westeros by Aegon I. After Aegon all kings carried Blackfire until Aegon IV gave the sword to his bastard son Daemon Blackfire after the boy was a tournament. Supporters of Daemon later claimed that the gesture meant that Aegon intended for Daemon the succeed him as king. Partisans of Aegon's eldest legitimate son Daeron II claimed that the sword was just given to Daemon because it was of no use to Daeron, who was no warrior. After he had been legitimized Daemon named his house (House Blackfire) to the sword.