Yep. Use a rotary Dremel type tool on clasps and cases (dismantled of course) on many occasions where polish and elbow grease are not quite enough. Not that risky, and in fact it can be the only way to get some deep, deep damage out.

Common sense is important here and excessive heat comes to mind as a side bar issue when using a Dremel, and in the case of some assembled watches that can be a source of concern with crystals. Especially acrylic ones. Disassembled is best.

Deep stubborn scratches can be eliminated with such devices, but its very, very important to get a handle on the amount of pressure, the length of time and the type of mop and polish to use. Do some testing first, if you can. You are not reshaping the case or clasp, so better to do in short bursts and check where you are going. Clasps are probably the best place to start as they are (in the main) disposable if it all goes wrong.

If they are light scratches, then you should not have any problems, but the above is still relevant. Don't over do the amount of time and keep a perspective on what you can achieve. It may not be possible to achieve perfection and light scratches on an assembled watch can cause other concerns. Dissimilar finishes being over polished by the mop, trying to miss features that could be wiped out by the power of a Dremel. Lots of masking tape to protect some surfaces you don't want to polish.

If its light scratches, they come out in a minimum of time. Always keep in mind though that for every deep scratch you are getting out, you are effectively removing quite a bit of metal to get down to that level. Its all relative.

No liability can be apportioned to any individual if an individual balls this up.....