Does swinging the katana at the floor, wall or just in the air have any benefit?

you can swing your katana at a bullet that you shot at a wall/floor to get a self bullet boost, like in godspeed. you can also swing your katana/fists to do death abuse in levels like clocktower or absolution. in any other level, if the slash isnt getting a parry or killing an enemy, its probably being done for fun.