Can white walkers be killed by Valyrian steel weapons, too? (latest television episode on HBO indicated obsidian weapons stabbing a white walker will destroy them)
The book has stated that the following things can kill the Others:
- Fire- This one is very well known, but might not be effective.
- Obsidian- This has worked at least once, but isn't really well known. The Wildings seem to have these weapons, and might know more.
- Valyrian Steel- This has been speculated, but never definitively proved. It was a discussion between Sam and Jon at the beginning of book 4 (And book 5) where this revelation came to play. Update: in episode "Hardhome" of season 5, it is shown that Valyrian steel can kill the White Walkers: Jon Snow kills one using his sword Longclaw. So as far as the TV show goes, this has been proven.
In answer to the specific question, "can White Walkers be killed by Valyrian steel?", the TV show has answered this in episode 8 of season 5, "Hardhome":
Yes, Valyrian steel can kill White Walkers in much the same way as Dragonglass. In the episode, Jon Snow battles and destroys a White Walker with his Valyrian-steel sword Longclaw, given to him by the previous Lord Commander.
It should be noted that, much like with Dragonglass, the effect of Valyrian steel on White Walkers seems to be magical in nature: it does not shatter when in contact with the ice swords/spears the Walkers use, and in turn it shatters the Walkers as well as their armor.
In this the TV show has progressed beyond the plot of the books, since George Martin hasn't yet shown us a battle with the Others where they are defeated by Valyrian steel.
The only two examples we have of weapons that can kill White Walkers are those made from Valyrian Steel and those from obsidian/dragonglass.
In season 3 episode 8, "Second Sons", Sam stabs a White Walker with a dragonglass dagger and kills it.
In season 6 episode 5, "The Door", Meera Reed kills a White Walker with a dragonglass spear.
In season 5 episode 8, "Hardhome", Jon kills a White Walker with his Valyrian steel blade Longclaw.
In season 7 episode 6, "Beyond the Wall", Jon kills a White Walker again with Longclaw when the merry men capture a wight.
These are the only White Walker deaths we have seen as of yet though it is speculated that dragon fire can also kill them. As for whether regular fire can kill them, well I doubt it seeing as the fire ring at the Three Eyed Ravens cave parted when they got near to it.
We have confirmation from Season 8 Episode 3, "The Long Night", that
Dragon fire can not kill the Night King and so presumably can not kill the White Walkers as well.
I would venture a *guess *- not supported by either the show or the books at this point (well, not that I know of), which is:
White walkers can be killed only by Dragon Fire, or by weapons forged with Dragon Fire.
If my guess is correct, then _naturally_occurring_ Obsidian might not kill White Walkers.
Please correct me if the books contradict my guess.