The edge is probably a bit thinner than 1mm (.04").
I would work it a bit more with 220 grit, and lean on the edge a bit as you stroke the sanding block downward. Once the edge is a small flat line, go to 400 grit.
If you are going to take Shotgunner up on the Cerakote offer ( very generous of him), you can stop at 220 grit. Shotgunner will give you the prep info needed.
If you are going to finish it by sanding, take it on up the grits to whatever point you decide to stop at. It can be 400 or 8000.....your decision on that.
Once the blade is either sanded or coated, you will put on the final edge.
This secondary bevel is what makes the knife sharp. It should be done on a wet stone at about 12-15 degrees per side. A two-sided or three sides stone is a good choice. Norton makes good stones. The two sided DMT diamond stones/plates are also good.
Form the edge on the coarser side, and once it is well shaped, go to the fine side. A few final strops on the back of an old leather belt will finish the job.
A tip on the final sharpening is to tape off the blade bevels, all except the last 1/4" at the edge. This will avoid accidental scratches on the blade by misplaced sharpening strokes. Duct Tape is good for this job. Gorilla tape is even better. Cut it to shape with scissors and place on the clean blade. Once the blade is sharpened, peel off the tape and clean up with acetone.