I don’t know how chainmail-specific your wish is, but there are plenty of weighted blankets for sale. Most of them have thousands of tiny heavy beads sewn into a quilted fabric that keeps them from moving around or bunching up too much. The one I have weighs about 8 lbs in Queen size and it feels, weight-wise, similar to the feeling of having four or five extra blankets on the bed but without all the heat/insulation of doing that.