Dark Sister is a slender Valyrian-steel blade, forged for a woman's hand, that House Targaryen carried out of the Doom alongside its larger companion Blackfyre. Queen Visenya, who flew Vhagar in the Conquest and trained with the sword in her father's hall, wielded it through the years of conquest and the long century after.
After Visenya the blade passed to a succession of Targaryen princes and bastards. It was last carried by Brynden Rivers (Bloodraven), Hand of the King under Aerys I and the bastard half-brother who slew Daemon I Blackfyre on the Redgrass Field. When Bloodraven was sent to the Wall in 233 AC for the murder of Aenys Blackfyre at Whitewalls, he took the sword with him; he is said to have ranged beyond the Wall and never returned, and Dark Sister vanished with him.