My experience as a left-handed fencer exactly.

Early on, I was among the best, but by the time it got down to reaction times and thinking about the next 8 places the blade was going to be, I was only average (if that).

Would have kicked ass on bronze-age conscripts, though. 20-ft lunge through the eye? I could do it with a short sword. Back in the day. Big survival advantage.

When young the gap between the best fencers and the lefties is smaller so the lefties dominate but as fencers get older the less talented ones are weeded out leaving a fencing talent difference that is partially negated by left handedness.

Why aren’t all the best fencers left handed then? Because the best fencers in the world have probably never fenced at all – it’s a fairly esoteric sport.

The early advantage gives lefties better performance, more motivation and maybe more coaching when young. This leads to an over-representation of lefties at all ages, but as far as performance goes the margin diminishes with age.