Ok I was a lightweight when I fenced, probably weighed less than a hundred pounds when I was 16 years old. Modern sport fencing is not predicated on upper body strength or overall power. Upper body strength will only come into play with beats and binds as a tertiary effect after skill and speed, while your lunges will be very slightly faster if you have strong legs.

I regularly lost to an 11 year old in my salle, mostly because he'd been fencing for four years and I'd only been fencing for two.

Strength or speed alone is not very useful, overall fitness (definitely including endurance and conditioning) and training is much more important.