User with this ability either is or can transform into a kamaitachi, Japanese yōkai appearing as weasels with razor sharp nails shape and length of long sickles. These weasels travel on whirlwinds to move at high-speed, slashing their victims with their sickles to inflict deep wounds. They move at such speed that they appear as the wind itself.
A legend has it that kamaitachi are three evil gods, working together to attack their victims: the first would knock down the victim; the second would inflict a deep cut; the third would apply medicine, partially healing the wound, causing no bleeding but a painfully large cut. Another legend is that the kamaitachi sucks blood from the wounds it inflicts, therefore the victims do not appear to bleed.
They're essentially the personification of the pain felt during a bitterly cold wind.