Good Morning Scott, one of the things that made my sheaths look a little better (IMHO) was to cut them a little large. Cut the welt, glue it up nice and snug, not worrying about how the cut edges look or fall (as in over or not far enough over the edge) because you cut it big to begin with.I then take it to my KMG with a 36 grt belt and shape it. After it's all glued up and "ground" is when I do most of my tooling, like the border grooves,using an edge beveler etc. I also cut the groove for the sewing and drill my sewing holes with a 1/16" drill (using the little wheel that lends symmetry to your sewing hole spacing). I do the sewing and the grooving part last, (after glue up and grinding) to insure nice even borders.I also do the sewing groove only on the front of the sheath until after it is drilled, the drill does not always come out the other side in the right place (in the groove) if you do it prior to drilling. Some things
have to be done prior to all that is described for obvious reasons, like sewing your belt loop on, tooling the front (in most cases), by that I mean such as basketweave type tooling, stamping etc., and a couple others I can't think of at the moment.I have recently thought about inserting a plate to do this (stamping the front)
after glueup & grinding also, just to make sure that ends up looking good and exactly where I want it to be. I know it's rather bass akwards but has made a big difference in how the final product turns out
for me. I left quite a bit out, can't think of the real names for the tools but I think you get where I'm going......I hope

Maybe you can take some of these things and apply them to your sheaths and if it helps....Great :thumbup: edited to add... after all is sewn up I wet the sheath, put the knife in it and press it in my kydex press to "wet form" them. Then its, deglazing, staining, atom wax & gum tragacanth on the edges
As stated in the below posts, Chuck Burrows video is really good ! The tips I gave are, like you asked, ones "you won't find in books" or video's, just little things I've found that have helped me. Read or watch vids all you can but the only way you'll really get better is by doing it more.......time & experience. I think Chuck B. is a Master Leather Worker, if I get half as good as him in my lifetime I'll feel pretty good about my leather work
