Why does it matter that she's a woman? Shouldn't the standard be the average human being? (considering that barely anything else takes into consideration gender other than succession laws and marriage)
If the standard was the average human being then there would have to be modifiers in the game to keep the number of strong/huge women down to more 'realistic' levels. And there is already plenty of events that takes gender into account.
Anyway, it's not a huge issue since it's only really a problem with Brienne since she starts out insanely stacked with good duelling traits. I personally think Brienne should 'just' be a level 3 fighter to compensate a bit so she's not the ~best fighter ever~ which isn't exactly what the book implies.