For that size job and for most knifemaking jobs for that matter - there are no machines that do that. The best IMHO is to do it slow and do it by hand. What striper28 has suggested with a file can be taken further. Think - Go Finer and finer till you polish.
The idea is to use a half-round file to make the initial grooves, then you can either wrap some sandpaper around the file, or I think the better way is to get a 12inch wooden dowel 1 to 1-1/2inch diameter (oak, not pine - too soft) from the hardware store and while you're there get sanding sheets (1 or 2 each) of 120, 240, 400, 800 and 1200grits if they're available. And get some OOOO steel wool. These things might end up costing you about $10 - $20 in all.
Wrap the sheets around the dowel and slowly take out the scratches from the initial file marks and work slowly with each grit grade, moving up till you get to 1200. as you get to 800 and 1200, any deep scratches will show up, so you likely will need to go back to a lower grit like 240 or 400 to take them out. It is quite important that you use the solid backing of the wooden dowel to get the best finish.
When you get up to 1200, you can start rubbing and polishing by hand using the steel wool. You may already like the slightly brushed finish at that stage. If you want to polish, use a metal polishing compound on the steel bolsters (if any). Use an oil like Danish oil on the wood bits - gives a beautiful oil finished shine - follow the instructions and leave for 1 week to get full hard, although you could handle it after a couple fo days.
Its best to work with a vice so you can use both hands, or you can use some C-clamps and fix the thing to a table. rRemember to wrap the blade in a lot of masking tape to avoid marring the finish there.
Its a lot of fun and a lot of knifemakers get started doing just this sort of thing. Good luck and I hope it helps. Cheers. Jason.
