For bigger radii a super fine cut file followed by a sharpening stone then polished with fine wetordry sandpaper would be the way I'd suggest. At least for the straight edges. For edges you want to keep the crisp look on but remove the ability to shave just a few passes with a very fine stone would be the trick. If you're looking to profile the whole area around the beavertail where the web of your hand takes a beating (I've got a 1911 so I know this is a bad spot) then some initial removal with a grinding bit or sanding drum on a Dremel would not be out of place but then switch to a larger smooth 1/2 round file then stones and then fine grit sandpapers again. If you don't have rounded stones then abrasive rubber wheels in the Dremel or some slightly larger abrasive rubber wheels in a hand drill or on a stationary motor would replace the initial file marks removal.
How fine you get depends on what sort of finish you want. However the key to a nice job is lots of elbow grease or electrical tool time to fully remove the scratches and gouges from the last step before moving on. Polishing is a matter of metal removal and you need to remove metal until you're down to the bottom of all the scratches from each step before moving on to a finer abrasive option. So it's important to not try to get too close to the final shape with the coarse tools. Leave a little shaping for the mid grade steps so they have metal to work with during that inital smoothening.
