Vintage West Germany Bundeswehr folding pocket knife.
 
This is the only one listed for sale anywhere that I can find with the "ST 80" mark on the tang!
 
Fantastic shape as seen in pictures.  I dont think this was ever used.  Few light scuffs on the main blade but I dont think it is from use.  Probably handling only (opening and closing) See pictures of the blades etc.
 
4 1/8" when closed. 
 
Location D2-15