Many uses and many people. The drop-knife by Peter Altenbach of Swan Werks, Ohligs-Solingen. Not really a takedown knife at just 100mm. but could land a "shock" thrust after a blow with a metal pipe. Filip Krapp used this method adding some additional lashing with a length of heavy chain in 1941. In Berlin Headquarters the "throwing" of gravel by the Geheime Staatspolizei could semi-stun also. Paratroopers carried the 5-function gravity knife in the Luftwaffe that had Deschler Skull and Assmann Eagle. Franz Walker Stahlecker kept one on his desk when having RSHA Gestapo joint meetings.