I'm just a dummy; Jerry Burney is the acknowledged expert in this area, and he posts pics occasionally of Luger "pulls" and/or lanyards...Here's a thread/pic he posted some time back -
http://forum.lugerforum.com/showthread.php?t=28419
Yours seems to be a home-made 'pull', much shorter than usually found, and could I suppose be called a 'field expedient solution' to the problem of getting a Luger out of its holster quickly...