There actually were several 'quick-draw' holster designs for the C.96 and the earlier Borchardt pistol - the Buffalo Bill Museum in Cody Wyoming had one a few years back, but it might have been on loan from the Frazier Museum. In any event, it was basically a normal open-topped holster sized for the weapon, rigged with a spring-mounted metal base down inside where the barrel would rest - the pistol muzzle would rest on the base which would be depressed down when the pistol was holstered. At the top of the holster was a spring clip that held the pistol in place - you would grab the pistol as if for a normal draw, and your index finger would be right where the spring release was - a quick flip and the pistol would effectively 'spring' up into your gun-hand.
I beleive the John Wayne movie 'Big Jake' had the Borchardt version of that holster later in the film.