If you're looking for mirror polish, you'll need to sand in a tight sequence of grits, then follow with a suitable metal polish like Flitz, Simichrome, Mother's Mag, etc. For most knives with a satin factory finish, a sanding grit sequence like ~320 > 400 > 600/800 (either or both) > 1000/1200 > 1500 > 2000 will get it pretty close, provided you make sure to completely erase the previous grit's scratch pattern at each and every stage (coarse scratches not removed earlier will really stand out, when the 'mirror' starts to show). Switch sanding directions by 90° for each step, so it's easier to see when the previous scratch pattern has been completely erased. If done well, by the time you get to 2000 grit, the blade should be very close to mirror, perhaps a hazy mirror. Polishing pastes as mentioned above can then be used to really bring out the mirror and shine.
Wet/dry sandpaper will produce a cleaner finish if used wet, with water or oil (mineral oil, honing oil, etc).
David