I think Tricod is on the right track. DMT makes good stuff. A lighter, cheaper, alternative is something like:
http://www.basspro.com/webapp/wcs/store ... erralID=NA
This one is from Bass Pro, but you can find similar items many places.
It's small and light, which is important for camping/hiking. You won't break it if you drop it on a rock, which is a concern with sharpening stones. The diamond surface will grind down nearly anything. You can sharpen serrated blades, plain edges, hatchets, or smooth burrs off of pretty much anything.
It won't put a hair-popping polished scapel's edge on your blades, but for camping an edge with more 'tooth' is, IMHO, a better all-around choice. Diamonds will put on a very serviceable edge, very quickly, and let you
touch it up easily.
The DMT product is higher quality. Diamonds are not all created equal, nor is the method of sticking them to the rod. But if you use multiple light passes when sharpening instead of heavy passes, the diamonds on the cheapie pen sharpener will last just fine.