2. The Stiff High Collar
The detachable collar sound innocuous enough, but in reality it was a deadly hidden killer. Known as the "Vatermorder" (father killer), this collar was designed to keep the necks of men straight and, er, erect (you can guess what parallels they were attempting to draw there).
This meant that they were essentially corsets for the throat. The stiff, high collar could easily cut off blood circulation and air supply, leading to death by asphyxiation at the slightest pressure or swelling, and there were even reports of the torture collars literally cutting through the neck of the wearer.