I know this will sound strange for a tip but believe me, it works. Not being the best quilter in the world, I find myself doing a lot of unsewing. As a result, I use a LOT of unsewing tools and they do get dull rather fast. Falling asleep the other nite, I got a brilliant idea. My DH was a salesman for professional knives for meat cutters. They have to constantly sharpen their knives. So do restaurants. They use a tool called a hone. I'm sure many of you have heard of it or maybe used it. My DH taught me how to hone my knives so I have the sharpest in town.
When I got up the next AM I took my dull unsewers and sharpened them on the honing tool. IT WORKED !!!!!. This will sure save money.