What type of knife, and what steel (if you know). It's going to take considerable work to fix it, and so unless it was something special I'd pass.
Note that the current "German knife" thing it to have the tip blunt (per the local Henkle's rep), so that flat spot may be factory. Huge pain to grind out, I have several German style knives with that "feature" I'm working on fixing. I guess the idea is that you will rock chop everything and open cans with the tip so it doesn't need to be sharp and won't dig into the board in use.
I would try sharping the whole length minus the up-sweep at the heel until the flat spot is gone and the knife is sharp to the tip, and just a bit extra on the "belly" if you want the blade a bit flatter. Make sure you de-burr carefully and completely. Use a coarse stone, you are going to have to remove quite a bit of steel if you have a flat spot.
Once you get the majority of the blade nice and sharp, see how you like the knife. You will also likely need to thin it quite a bit after you fix the flat -- this is why I'd not suggest a rescue unless the knife has some significant value to you. I'd not be happy spending another dozen hours on a junk knife as I did on my first practice thinning exercise (ended up on the bench grinder for that one, cheap knife with a very fat profile). If you like it enough to keep going, 2mm is a HUGE amount of steel to remove by hand, you are going to end up buying a belt grinder to finish it!
If you bread knife it to the profile you want, you will essentially need to re-manufacture the grind and bevels, and I'd suggest power tools, not hand grinding.
Peter
