Daemon receives Blackfyre

"King Aegon knighted Daemon in his twelfth year when he won a squire's tourney (thereby making him the youngest knight ever made in the time of the Targaryens, surpassing Maegor I) and shocked his court, kin and council by bestowing upon him the sword of Aegon the Conqueror, Blackfyre, as well as lands and other honors. Daemon took the name Blackfyre thereafter."
- The World of Ice and Fire, George R.R. Martin