Have one too, bought it 6 years ago on the bay at the time. I had it reground by Rory Connor knives in Ireland for 25£, good price and he tightened up the sheath as it was working loose. The grind was convex and a nightmare to sharpen. Now its not so bad, a real rough work tool, 4mm thick is great for tougher jobs but it still wont get an edge like a carbon steel mora, in fairness is that not true of most 01 knives?
Anyway, its a rough tool really, not really suitable for fine work, and still hard enough to get a decent edge, I use Japanese water stones, and wet and dry plus stropping, no joy really. You get what you pay for with this knife. Wouldn't really recommend but a tough beast if thats whats needed.