You're right, CFL40, I was over-generalizing. They had to pass a law in Ancient Rome banning the daughters of senators from fighting in the arena. Since the women or girls in question obviously weren't slaves fighting for their freedom, nor prisoners who had previously been condemned to death, nor women forced by economic hardship to fight to provide for their kids, these must have been 'affairs of honour' and the decree would hardly have been necessary if it hadn't all been getting out of hand.
One contemporary account of a duel fought in 1609 between two women in France indicates that such encounters were not even rare. Same story in Germany and even in devoutly Catholic Mexico, where two high society women fought a duel topless as recently as 1900, a scene later immortalized on its packaging by a popular brand of cigars. But, as you say, these were all disputes between wealthy women. The working class wouldn't even have been able to afford the swords let alone fencing lessons.
I'm sure you're right, too, in saying fights between girls in posh boarding schools were probably hushed up a great deal of the time. In others, where girls were taught judo, fencing or even lacrosse, encounters of a more muscular nature between the young ladies were clearly not frowned upon at all.
In working class districts, it seems to have been a patchwork; I heard Anthony Burgess say once on TV that where he grew up, most of the fighting was done by women. There was a district in Victorian London (when literally millions of Londoners either were surviving through prostitution or had been forced at some time or other to sell their bodies for cash) that was so dangerous, Charles Dickens used to ask a policeman to accompany him when he visited to do research for his novels. His very first book ('Sketches by Boz'), published under a pseudonym, features an account of a fight he witnessed there between two women.
So you're right, I was over-generalizing but I think my basic point holds.