Flitz or Simichrome are good from what I've heard.
Personally I let my Khukri's naturally develop a patina with use. The marks and discolored areas help tell a story. Use, Wash, Dry and put away is all I do.
If you get some scratches in the blade, Wet/Dry sand paper and some oil helps to get them out. Grit depends on the scratches. After you get the scratches taken care of, use the metal polish to restore the shine. Sometimes I've had to remove rust from blades. They end up with a nice satin finish after cleaning. Never saw the need to restore the mirror finish.