"Tameshigiri", literally "test-cutting" iirc. Usually performed by professional sword-testers, "shitoka". Perhaps not the most skilled samurai even in the field of swordsmanship, but expert in their particular art.
On the Wikipedia page
https://en.wikipedia.org/wiki/Tameshigiri there is the account of the "condemned criminal who, after being told he was to be executed by a sword tester using a Kesa-giri cut, calmly joked that if he had known that was going to happen, he would have swallowed large stones to damage the blade." (Described as apocryphal; iirc this is found in The Sword Book in Honcho Gunkiko, one of the two books published together in English translation in "Sword and Same".)
http://www.japaneseswordsmanship.com...shigiri_h.html