Check the latest rules ... they're here on the website somewhere. Hunt around.
I know when I was fencing, it was legal in one of two situations: (a) at the rank beginner's level, and (b) if somebody kep getting disarmed, sometimes a judge would make a martingale mandatory. If you're fencing in upper level competitions, it becomes a non sequitur -- by then, you should have developed enough of a grip to be able to control your weapon. If not, then it's back to the drawing boards.
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Salute!
Youth and enthusiam are no match for age and treachery....
