Thanks for the kind words again, fellows.
Well - I just took a little time to sharpen this knife. I used my standart 320 grit stone and then three finer stones until I come down to leather strop. The D2 performed very great without any problem. I sharpened every blade at an angle of 20° per side and everything is fine. The three blades are razorsharp now. I was surprised that the D2 was so easy to sharpen. I feared, it would take a long time and a lot of material loss. But it just works great.
(Sorry - I didn´t take some "Before"-pics, but here´s the result)
I was a little worried, because I read all the stories here about the hardness of that steel and that it (can be) impossible to sharpen. The blades are as sharp as any other of my pocket knives.