I have quite a few two-bladed SAKs secreted in assorted places. On these, I like to take the small blade to a very acute polished edge of about 10 degress (per side). It makes for a *really* good cutter; ideal for slicing through soft materials like flesh (to remove splinters, fish hooks, whatever - done that a few times). Not much good on harder materials as the edge will start to roll if you don't keep a perfect technique, although I've used it carefully on softwoods without a problem.
I do the small blade on 3M brand wet'n'dry paper on a flat aluminium plate, starting at 240 grit and working up to 1200. Then I polish up further on strips of cardboard loaded with diamond paste, working down to 1 micron. Then finish with a dry strop. You could just go from the 1200 grit to a strop; wouldn't make too much difference I don't think, if any.
On the larger blade of the two, I do one of two things depending on what mood I'm in:
1. Use a 15 degree grind. I put this on initially by hand on the 240 grit sandpaper, then finish off on the sharpmaker with the brown, then white rods, then strop. If I had courser sharpmaker rods I would just use that for the lot.
2. Convex the larger blade with sandpaper on leather. This takes longer to do but looks really pretty when polished up. Not sure if it really increases cutting ability much over the flat bevels.
For the bigger SAK's, the ones with locking blades, so far I have just used flat grinds but have two different areas of finish on the blade. I get an angle of 15 degress with the 240 grit sandpaper, followed by 400. Then, on the edge nearest the handle for about half the blade length, I'll progress down to 1200 grit to remove the courser grind marks. The tip-end half of the edge stays at the course 400. Finally I'll polish the whole edge on 5 micron down to 1 micron diamond paste. This gives a tip end that is a really good slicer with a bit of bite due to the polished 400-grit 'teeth'. The rear edge is a great push cutter for making fuzz sticks or whatever.
I keep the edges acute, rather than going up to 20 degrees for instance, because I see the blades primarily as light-duty cutters, like a Mora (which I don't have), not really for heavy use. The larger SAK's could be batonned carefully I suppose, but I've never needed to. I might reconsider this if it was to be my *only* knife in the outdoors.
Another thing to bear in mind is how easy the edge is to sharpen in the field, if you think it's likely you would need to. I think that comes doen to personal preference - do you prefer/find it easier to work on a flat edge or convex?
Keep 'em sharp,
Rick.