cant be sharpened out in the field at all?
Utter nonsense!
First, if the convex ground/edged blade is sharpened before you go out, you'll need to be out a very long time, or start chopping moose bones, before you need to sharpen it again.
Second, you can sharpen a convex ground knife on type of stone/grit/etc you could sharpen a bevel edged knife on. I've done it for decades. I've sharpened convex edges on Arkansas stones, diamond stones, river stones, and coffee cups. The mouse pad and wet.dry sandpaper just make it easier. But as long as you do it by hand, and try to keep a feel for where the edge is at, you'll be fine.
Now if you don't have clue one as to how to sharpen freehand, start learning now!
Finally, the whole stropping thing is not just a "convex" thing - it's a reality for any knife edge that if you strop it with a compound loaded piece of leather, yor edge will stay wonderfully sharp for much longer. Stropping the edge on your pants leg doesn't work quite as well, but works better than nothing.
If you feel the need for a minimalist convex sharpening kit to cover all eventualities, get a small, fine DMT stone, glue a piece of leather on the back, and crayon some black compound on it.
But personally, I just use the river stone and my pants leg! :thumbup:
If you'