Valyrian weapons are unique weapons to the game which do not break but are difficult to acquire. They are also able to damage whitewalkers and wights.
Valyrian steel is an ancient material that is no longer able to be forged. The material originated in the Valyrian Freehold, an ancient kingdom that utilized dragons in warfare. No one knows exactly how Valyrian steel is forged, however there is speculation that it was made by the heat of dragonfire, which would not be too much of a surprise considering how much the Valyrians treasured their dragons. Either way, the secrets to making Valyrian steel was lost in the Doom of Valyria, and has never been found again. Valyrian steel blades are far superior than any other sword one can find, even the best castle forged steel. It is stronger, lighter, and much sharper than any other material that has been discovered. Not only this, but Valyrian steel can also be used to kill white walkers, and it is impossible to break, making them much sought after weapons. Because no one knows how to forge Valyrian steel, the material is extremely treasured among those that have it, and also extremely expensive. Dying houses often will sell everything but their Valyrian steel swords, showing exactly how rare they are, and there is even a man rumored to have a full set of Valyrian steel armor, that man being Euron Greyjoy. While Valyrian Steel cannot be made, there are people who are able to reforge it, and inside of the walls of Qohor there are smiths that can reforge Valyrian steel into new weapons, though they are rumored to charge a pretty penny for the service.
1 or 2 handed Valyrian sword
A valyrian sword can be acquired from the weapons merchant in Qohor. You will need a renown value of over 600 or else the merchant will not accept you and tell you that you are not well known enough. You gain knowledge of the merchant in Qohor selling weapons via rumors from tavern keepers.
The merchant can make either a two handed greatsword or a two different one handed swords. They cost 90,000 or 120,000 each respectively. Note that if you choose the two one handed swords that one sword will have better stats than the other, this is presumably because the other sword had less valyrian steel to work with.
Enhancing the valyrian sword will result in a masterwork version which is visually different from the normal grade.
As this is a valyrian steel weapon it can be used to fight white walkers and it is also impossible to break.
Pre-owned Valyrian Weapons
A Number of lords in the game own a Valyrian Steel weapon. You can take it from them by either executing them or sending them to the wall, however it should be noted that if you execute a lord that every lord in the realm will be against you, and if you send a lord to the wall then every lord in that specific faction will be against you. Sending a lord to the wall or executing them gains you all of the items in their inventory, though it is usually recommended to just send them to the wall after you have taken all of the useful lords from a realm. Lastly, you can only send lords to the wall or execute them if you are king or queen, meaning that you will need to own kings landing.
Longclaw is the ancestral sword of House Mormont and has been for the last 5 centuries. Lord commander Jeor Mormont eventually retired from his position as head of the family and as a lord. Once he had done so he headed to the wall to take the black, and eventually became the rank of Lord commander of the Nights Watch. The sword was supposed to be passed onto Jorah Mormont after Jeor Mormont took the black, but after Jorah Mormont went into exile for selling poachers into slavery, the sword was given back to jeor Mormont. Years after this event the sword was given to Jon Snow, a bastard of the Great House Stark. He had the pommel of the sword reshaped into a direwolf, the sigil of House Stark.
Long Claw is owned by Jon Snow, a member of the Nights Watch. Unlike most others who own Valyrian weaponry, Jon snow is not a lord and the weapon must be acquired in different ways than normal. To get Longclaw, Jon must first be captured and be a prisoner. Upon rescuing him (ex: siege), you can ask him to join you, alternatively you can take him prisoner and ask him to join you as well. Once he is a companion, you can take his weapon and any other item in his inventory.
Ice is the ancestral Greatsword of House Stark. It is described as being a massive blade that is taller than a full grown man, and as wide as someones hand. Because of the fact that the sword is so massive it has enough steel in it to be able to make two entirely new longswords. The heirloom sword has been in the Starks possession for 4 centuries. The sword has been used in both warfare and celebrations, though it is often-most used for executions. The sword was forged in ancient Valyria before the doom, and has been passed throughout the Stark family for several generations.
As Ice has no owner you will need to obtain it in a nontraditional manner. To obtain Ice you have to conquer Winterfell then look for the Weirwood tree, there will be a chest underneath the tree with Ice.
Item ID: 1036
Blackfyre was the most famous sword of House Targaryen and perhaps the most famous Valyrian steel sword to date. The sword was once wielded by Aegon the Conqueror, the man who conquered all of westeros. (with the exception of Dorne.) The swords blade is a smokey black color and it has been the premise for an entire rebellion. King Aegon IV Targaryen passed the sword down to a warrior named Daemon Waters, his bastard son. He chose to give this man the sword over his own legitimate son. Daemon Waters eventually renamed his last name to Blackfyre and created House Blackfyre. The sword was viewed as a royal weapon that was passed down from kings, which eventually led to the first Blackfyre Rebellion, a bloody conflict that led to the deaths of many dragons and Targaryen family members. Eventually after the rebellion was over a man by the name of Bittersteel took the weapon to essos where he created the golden company with the intentions of sailing back to westeros one day and reclaiming the throne, rumor has it that the weapon is still passed down through their line.
Blackfyre is with Daenerys or Aegon, depending on whether you chose books or TV version. Note that the sword will always be with the targaryen invader, no matter which version you select.
Dark Sister is a sword owned by House Targaryen that was designed for a woman's hand, as evidenced by the slender grip. The weapon was put to very effective use by Visenya Targaryen, one of Aegon Targaryens sister wives. She assisted in his conquest of Westeros atop her dragon with this sword in hand, and it was even used to save Aegon during an assassination attempt in which the guards were unable to react in time. Aegon insisted that his guards were adequate enough to protect him, but when Visenya drew dark sister and cut Aegons cheek before the guards could react he let her train his Kingsguard. Over time the sword was passed down through the line but eventually was lost during the Blackfyre Rebellion, never to be seen again.
Dark Sister is in the modification but it is unknown if the weapon is attainable without cheats. Either way, in the future it is likely to be put into some sort of quest.
Heartsbane is the ancestral sword of House Tarly. The sword has been in the possession of the house for 5 centuries, and is treasured as such. The hilt is mentioned to be wrought in the shape of a bow and arrow, and the crossguard forms the limbs of a bow. Both of these features reflect House Tarly's sigil, The Huntsman. Like other swords of its type this sword was made in the Valyrian freehold and is kept close by on a mantle inside of Horn Hill, House Tarly's castle.
Randall Tarly is the owner of Heartsbane.
Item ID: 1039
Khal Pono has a Valyrian Arakh named Crescent Shadow. Crescent Shadow has been forged out of Valyrian steel from the blade of an adversary of a great Khal long ago and has been wielded by a number of Khals overtime.
Brog Matter wields the Valyrian steel blade Dark Vengeance, upon which Brog swore a blood oath to avenge the death of Rhaegar and the fall of the Targaryen household. Brog obtained the Valyrian steel sword through slaying its previous owner Lord Rogare of Lys.
The companion Reed Matter has in his possession a Valyrian steel sword named Reapers Vengeance. After Rhaegar died, Brog and Reed went on many a grand adventure together. They scoured the land beyond the Wall in an attempt to find a tomb where a legendary blade of a long past Wilding Warlord was rumored to be buried. After much searching, they eventually discovered the tomb and its entrance. Deep in the tomb, Reed found a beautiful and deadly Valyrian blade clutched in the skeleton hands of a long dead Warlord. Reed named the sword Reapers Vengeance.
Adrien Celtigar of House Celtigar of Claw Isle wields a Valyrian steel axe. House Celtigar is an ancient and proud house, with the blood of old Valyria in its veins.
Lord Monford Velaryon of House Velaryon possesses the Valyrian sword Sea Serpent.