G'day
I don't want anyone to get the impression that I think that WotC have to use 'cold iron' to mean anything in particular, or even nothing in especial. They are perfectly free to declare, for example, that they mean iron that has been refined, smelted, and shaped using Fabricate in the absence of significant heat--or anything else, really. All I am saying is that until they tell us otherwise, the only thing we have to go on is what the phrase means in established usage.
Suppose, for example, that we read references to a monster called a 'poptepet': that might be absolutely anything, because the word has no established meaning. But if we hear of a 'thylacine' it'd be just silly to assume that it could fly. The word has a meaning in established usage.
So the question becomes this "Does the phrase 'cold iron' have a meaning in established usage?' None is listed in a dictionary that I have consulted (yet, though I have hopes of the OED and Brewster's). None is mentioned in any work on metallurgy or history of industrial processes that I have ever read (but I am not an expert in either field).
But I have certainly heard the term bandied about in books on folklore and in fantasy stories. Can we work out what those writers meant?
Only one of those authors (Kipling) is prominent enough to make it into a book of quotations. In the poem cited, 'cold iron' refers to weapons and possibly armour made of iron and steel. In other works inspired by the history and folklore of the region in Sussex where he settled, Kipling uses the term for ordinary iron items such as nails, a cast-iron bathtub, a knife, and a slave-collar.
I vaguely recollect reading a collection of English and Irish folk stories (collected, I think, by Roger Lancelyn Green) in which characters were saved or protected from fairy magic by, for example, chancing to touch some nails they had in their pocket. I can't remember whether the phrase 'cold iron' was used, but that is certainly some suggestion that ordinary everday iron is inimical to fairies in those beliefs. And besides, that isn't enough of a reference for anyone to check (and given the floods of contradiction and extraordinary claims that are flying about in this thread, people should certainly be checking everyone's references).
Does anyone have a collection of European folk stories indexed by theme? We ought certainly to be able to determine whether in folklore it was ordinary iron or something special that crippled elves, fairies, and magic.
We have to be a little more careful about considering what fantasy writers meant. On one hand, many of them are consciously innovating, so the magical situation in their works is deliberately different from the established. But on the other hand, even when they innovate, their innovations can be influential, and other people will take up the meanings that they established. So it would be worthwhile if anyone has a fantasy novel to had in which 'cold iron' is specifically mentioned, in which something or other makes it clear what the author meant by the term, would cite it. For instance, if anyone has a copy of Poul Anderson's The Broken Sword to hand, it would be very useful if they could check whether the elves and trolls in that were unable to handle any iron at all or only special iron of some sort.
I'm off to the library to check Brewster's.
Regards,
Agback