So I ordered a few samples of the Italian Mesh Ribbon the Michele Carragher has used in some of her Game of Throne embroidery (like Cersei's red dress) and I thought I'd share some pictures of it with you so you can get an idea of what it's like. It comes in a variety of widths but regardless of width all of the ribbon is essentially a metal mesh tube. And all widths have the same property - you can stretch and pull it to create amazing net designs. This stuff is really, really cool.
This makes it really useful for creating curved designs without having to pleat and for creating 3 dimensional effects. I don't know a whole lot about historical embroidery techniques or materials so I can't speak for the historical accuracy of the ribbon but I can imagine many fantasy costumes being embellished with it.