The certificate reads:
In the Name of the Leader and Supreme Commander of the Wehrmacht, I award to Sergeant Wilhelm Kriessmann the Iron Cross 1st Class ... 20 January, 1943.
It is signed by Ritter von Greim but unfortunately the signature doesn't show up on the copy.
Pictured below: Col. Gen. Keller of the Luftflotte presented the awards and visited with Willi's squadron. I'm sure that is Willi in the picture on the left.