Japanese craftsmen have for many centuries manufactured the most formidable weapons. Historically swords were tested (tameshigiri) on human bodies purchased from the execution grounds.
The finest swords were tested on multiple bodies tied together. One famous old Japanese sword was inscribed on the tang that it had successfully sliced through seven bodies with a single cut !
The bodies were carefully inspected before cutting to check for disease, primarily because it was believed that sickness would make the pure sword unclean. After each gruesome cut, the sword and the target were carefully examined to determine if the edge had been notched and that the cuts were clean.
During the Meiji period test cutting on the bodies of criminals became illegal. These were replaced by targets made of soaked and bound wara (rice straw) with a bamboo core.
We must assume that all of the Samurai swords would have been deemed worthless after dispatching the Ogres of Oeyama........