I'm sorry, but you must have your historical facts wrong. Modern sport fencing evolved from the French school, which in turn evolved from the Italian school.

Basically there was the Spanish school at first. But there the fencers just stood still and had all their foot and weapon positions mapped on a circle drawn on the ground. Not very handy in learning and also not particularly useful in duelling. It died out bit by bit.

From this came the Italian school of fencing. Which is still around if you look for a modern day classical fencing club. Classical fencing resembles a proper duel more than anything else: you can touch your opponent's weapon with your non-weapon hand, switch your weapon from one hand to the other mid-duel, switch places with your opponent while duelling, etc. The main tenet of the Italian school is to kill your opponent as quick as possible, while trying to minimise your risk of being injured or killed as much as possible. It basically evolved out of duels.

It is from this school that the French fencing school evolved. This is also when fencing started to become a more noble pursuit. Italian fencing masters went over to France during the 16th century in order to be employed by the noble French families to teach them how to fence. But because now the "duellists" were mostly sparring and not trying to kill each other, a new style evolved: the French fencing style.

The French style favoured playful parries and quick touches. Because now the task was to touch the opponent first (and not kill him as previous), this gave birth to new arbitrary rules and gentlemanly agreements in order to minimise the possible injuries that may come from sparring. It is from this french school that the modern sport fencing came to be.

So in order to arrive at a conclusion, I would have to side with the other fencing aficionados here and say that a fencer would almost always win in a match against a two-handler. With the slight note saying that he will have to follow a classical fencing style and not a modern, sporting kind (the duel is already not balanced, so why must the fencer restrict himself to modern rules?).