|It can be repaired by darning, using silk thread and a very fine beading needle. I use a magnifier hung around my neck, and good light for such a project. It all depends on how much time you want to spend on doing such a precise job.|
First, surround the 'worn' fabric with simple running stitch, then literally weave the long threads 'under and over'. OR;
If the worn sleeve is below the elbow, you could make it into a short sleeve summer shirt.
Hope it's not too late.