I have an old Singer seam ripper from the 1930's. It's the equivalent of a single edged razor blade that folds into a handle and has a needle threader on the other end. It's what I used from the time I learned to sew until I moved away from home after college. Now I pick out stitches from the top with the tip of a ripper, but never use it for cutting threads so dull doesn't matter to me. :lol: