Fallknivens great DC4 sharpener.
These are unquestionably the best sharpeners on the market, well made, field expedient and,well, good at sharpening knives. Highly recommended, these sharpeners are sold all over the world. If you buy a knife I strongly advise you buy a DC3 or DC4 to go with it. One side of the stone is diamond whetstone (25u) and the other side is a fine ceramic whetstone. Restore the profile with the diamond side and then polished to a razor edge with the ceramic. Both stones are sold with a leather pouch
The DC3 is 25mm by 75mm and the DC4 is 32mm by 100mm.