RK, you don't post on the forum near as much as you should! Nice to hear from you.
Thanks for the interesting photo and translation...
Yeah, the Luger could be fired ONCE, but not with any reliability for more than one shot...
...and if you were a paratrooper, and needed your pistol fast, how would you like to have to get that belt buckle undone and get your pistol out in a hurry because of a firefight?
As the famous U.S. Border Patrolman, and author, Bill Jordan used to say... "There is no second place winner in a gunfight."
An interesting carrying design for perhaps attachment to a backpack, but likely just a use by a leather cobbler with a buckle/belt for which he had no other purpose... Looks like he wrapped it around a Luger and had an idea... a bad idea.
Just my $0.02