I'd just seen the film, and, as it happened, a colleague at work was a national-level fencer. I asked her whether Liam Neeson's unorthodox manoeuvre in the final sword-fight was legal.
She considered the question carefully. Well, she said at last, in a normal competition it would of course result in immediate disqualification. But in a fight to the death it was probably acceptable.
So now you know too.