Do you mean this costume
If so, while I see the similarities, I would still put my money on arrow smocking and embroidery. The embroidery being what is the texture that's a slightly different colour from the fabric.
I have doubts that the felting could produce results that uniform and controlled, and although there's creative license since it's fantasy I have doubts that a costume designer who is so into historical production methods and stuff would use a technique pioneered in the 1990s.
Please don't take that as me being a rain-cloud ! Just group-think - when we think together and each examine things we can accomplish more !