At the club level it's not atypical to see mixed gender, but in the professional level it's split by gender. I think they can get away with it being mixed at lower level of competitiveness because gender doesn't matter as much as in other sports. However, from what I've seen, size/strenght/weight definitely do play a factor in the sport and it does favor men.

Edit: By club level I mean like university fencing clubs. At the club level competitions can be mixed gender or split gender. Anything above club level is split gender.