If you can find a more sententious source than me, buy it!
Unless for some reason you can't use those techniques on Valerian steel. Because it's magic dragon steel or whatever.
I will remember this evasion the next time there's computer hacking in a film.Valerian steel is explicitly made with magic and technology that's consistent with the late medieval society depicted. Cold rolled is a much more advanced technique and its existence would have left marks all over Westeros not just the gate at The Wall and Castle Black. Considering that The Wall was also made with magical assistance, they could have claimed that.Instead the writers went with a modern term, even worse; a modern term that speaks of economical manufacturing rather than strength (although cold rolled steel will be stronger than unrolled).
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