Herr Pieper, not an Imperial WW1 entrenching tool set, the Model 1874, Model 1898/99, and the Model 1898/1909 were the model of spade carried by Imperial infantrymen, all similiar, but differing in some detail, however all these patterns of spades had riveted blades. So succesful was this type of spade that a nearly identical model was used after WW1, these shovels can be recognised by their lack of rivets on the blade, such as the one you have. A completly new model appeared in 1938 (the "Klappspaten"). The eagle stamp is of Wiemar period Reichsheer use.
Hope that helps.
Prost ! Steve.
"The German Army is the perfectly adapted, perfectly running Machine. The difference is that the Germans are organised with a view to War...with the cold, hard, practical and business-like purpose of winning victories."
G.W. Steevens - The Daily Mail (1897)