I have a Bark River Gunny Sidekick in CPM M4 that I really like - Bark River really seems to nail their heat treats. The best way to sharpen a convex edge is to not let it get dull - strop it between uses. I am rather partial to the white compound preloaded strop sold by knives plus:
https://www.knivesplus.com/leather-sharpening-strop-white8.htmlIf you let it get dull, everything you wanted to know about sharpening convex edges:
https://youtu.be/BsWCk4Ttqe4David
