Many of the great houses have heirloom blades made from Valyrian steel. Where did they get them from? Did they buy them? Gifts from the Valyrians? And is it known how old they are?
- They were probably brought to Westeros by the Targaryens after the Doom of Valeria, 400 years ago. Keep in mind that the Targaryens are of old Valyrian lineage.
The Doom of Valyria was a volcanic cataclysm that took place approximately four hundred years before the War of the Five Kings.
It is likely that most of the Valyrian steel swords were brought to Westeros by the Targaryens, after the Doom of Valyria.
The Stark sword, Ice, is at least 400 years old, from around the same time as the Doom. Heartsbane is 500 years old.
List of known Valyrian steel blades
- Blackfyre - An ancestral sword of House Targaryen, wielded by Aegon the Conqueror and Daemon Blackfyre. Lost after the Blackfyre Rebellion.
- Brightroar - The ancestral sword of House Lannister, carried to Valyria and lost by Tommen II Lannister, King of the Rock.
- Dark Sister - An ancestral sword of House Targaryen, wielded by Visenya Targaryen, Prince Aemon the Dragonknight and Ser Brynden Rivers. Lost after Ser Brynden's removal to the Wall.
- Heartsbane - The 500-year-old ancestral sword of House Tarly and currently wielded by Lord Randyll Tarly, and soon to be passed to his son and heir, Dickon Tarly.
- Ice - The ancestral sword of House Stark, well over four hundred years old. Captured by the Lannisters after Eddard Stark's execution and melted down.
- Lady Forlorn - The ancestral sword of House Corbray and currently wielded by Ser Lyn Corbray.
- Longclaw - The ancestral sword of House Mormont. Abandoned after Ser Jorah Mormont's disgrace and sent to his father Jeor Mormont, Lord Commander of the Night's Watch. Passed by him to Jon Snow.
- Nightfall - The ancestral sword of House Harlaw. Currently wielded by Ser Harras Harlaw.
- Oathkeeper - A new sword forged out of the Stark sword Ice and given to Jaime Lannister by his father. Passed by Jaime to Brienne of Tarth.
- Red Rain - The ancestral sword of House Drumm, forged before the Doom. Currently wielded by Lord Dunstan Drumm
- Widow's Wail - A new sword forged out of the Stark sword Ice and given to King Joffrey I. Currently in the possession of King Tommen I Baratheon.
It is not mentioned in the books where the swords come from, except that they were spell forged in Old Valyria. Presumably they come from either trading with Valyrians, or from the Targaryens who conquered Westeros.
I do belive it is hinted that Ned Stark's sword Ice is about 400 years old.