Used as an efficient way to cut the ears from the victim. The helmet was placed on the head; the ears sticking out just under the blades. All it took was a quick chop and the ears would be amputated.
Possibly also used as a torture device – just the idea that the ears would be removed may have been enough to make the victim confirm any of the torturer’s suspicions.
Trivia & Comment
This device is only featured in one reference and in a fleeting paragraph – it could be considered something of an apocryphal device and its existence is up for debate, although it makes for a great story.