This was the Scissor Kick from Brazilian jiu-jitsu, one of Black Widow's signature moves. At the same time, it was a classic technique for overcoming strength with weakness. The neck was an inherently vulnerable part of the human body. No matter how powerful someone was, it was difficult to train that area. Meanwhile, the legs were where the body could exert its greatest strength. Using one's strength to strike the opponent's weakness! Even someone far stronger could be tripped by this move, or even have their neck snapped!