In The Merlin Conspiracy, this elderly man is a member of a family of impoverished nobodies in the world of Loggia City. The family is encountered by Nick Mallory (Nichothodes Koryfoides) when, stranded in Loggia City and uncertain how to get out of some trouble he's in with the law there, he is trying to find a way to track down the enchanter Romanov.
The family, like many in Loggia City, spends nearly all their time doing embroidery work that will be sold for a pittance to the wealthy and privileged class in the city. These are presumably the Prayermasters and others who own businesses or property to a degree that lets them live in protected areas and spend their wealth on items like embroidered clothing. Meanwhile the poor, including the weaver's family, must live and work in the upper levels of the city, where they're exposed to solar rays that cause dangerous and disfiguring skin lesions and tumors.
The Green Weaver himself has developed new types of patterns, executed in various shades of green, that he and his family members are trying out, although he isn't sure that people will want to buy them. He asks Nick for his opinion on the designs, and when Nick tells him they are beautiful, and that he himself would love to buy them and hang them up so he could admire and enjoy them.
Grateful for this information, the weaver sends a family youngster to guide Nick to a level of the city where he should be able to find the path that leads to Romanov's world. Eventually we learn that he and his family ultimately benefit from Nick's information.