Let me begin by saying how much I've enjoyed reading your "Song of Ice and Fire" series. I was first drawn to them by a comparison to the Wars of the Roses, having always been a Yorkist (even having a fondness for Hunchback Richard!).
Me too. Shakespeare's Richard is a great character, even if he doesn't have much to do with the real historical Richard.
A brief question about Valyrian steel - is it the metal that makes the sword so special (provenance, age, etc), or is it the forging (spells, techniques)
Forging techniques and spells, actually. There is magic involved in the making of Valyrian steel.
In other words, if a smith knew how, could he take some fresh, high-quality steel and produce an equally fine sword?
Not unless he could work the magic.
Or is it something like Aragorn's Anduril in the Lord of the Rings, which could be re-forged but not made from scratch, or so it seemed to me.
That's pretty much been the situation since the Doom of Valyria.
Having suffered through one of the coldest Decembers - and I live in Winnipeg - in well over a hundred years, I have a great deal of sympathy for any person, fictional or not, who faces several *years* of winter. Am I right in thinking that by the beginning of your next book, Westeros will be buried in snow? Brrr...
The really bad weather won't be along until THE WINDS OF WINTERS, but yes, there will definitely be a chill in the air come next book.