Very Light Armor is made from cloth by tailors. Cloth is made from yarn and thread which both come from the root foraged in each tier.
As a 25 tailor, I haven't yet seen any actual robes but then I've never equipped any of the VLA pieces I make.
It is possible that the shirts and pants actually look like a robe once they are being worn...
You can find further information about tailoring at http://eq2.eqtraders.com/articles/news_page.php