Page 83 of witmans luft book holds the key

1st model lufts prior to 1937 had the option of 1st model luft engraved blades, More than likely after that one would have gotten a 2nd model luft with engraved blade
#1 cheaper
#2 More readily available
#3 Less time and effort to make
In the slim chance that this blade is legit have a fun time selling it....
White elephant
Manfred i disagree the eagle on the dust jacket dosent appear to be the same

"Drive Fast and Take Chances"
Author... Roy Carroll