Argh, nightmare! I've had the fraying problem with metallics, and it's so maddening! Timeless Stitches, the little needlecraft shop up by the winery, always says "Use beeswax!", but I've always found that to be more hinderance than help.

Half the reason the big heron marked blade I stitched for David years ago took so long was because the silver just really liked coming apart.