Gonnate,
My stuff is hand stiched holsters 8-9oz with a 6-7oz lining. I back stich 3 or 4 times, cut the thread off close, and then I take a needle, or the awl and poke any remaining thread down into the last hole. I have holsters that are seeing heavy use in competition 3 weekends a month over four years and I have never had one come back with loose thread.
Some of you other gents had some good ideas that I may "borrow".