I think hoof is right, there is some bug with the charge bonus being on or off; last night I had men dying when some General Bodyguards were u-turning out of my infantry mass. It wasn't just kills from the knights swinging because entire clumps of men unlucky enough to be beside the horses just died as well. It would have been comical had the 40 bodyguards not killed 400 men just by turning around in my formation.