In the 15th century, Jean d'Arc lead the French to a formidable sequence of victories over the English occupation, and this seems to have set up a small boom in imitators. Quite a few queens and ladies, including Queen Elizabeth, Catherine of Aragon, and Mary, Queen of Scots, all donned armor and rode in front of their armies to act as a rallying figure. Unlike Joan, they functioned more as glorified mascots rather than exercising actual military command.
In the New World, women were relatively rare during the conquest phase. The Spanish Crown permitted women to travel only with the protection of male relatives. A few
conquistadoras were known to have participated in battle, including
Maria Estrada, who rode with Cortes' cavalry, and
Ines de Suarez, who ruthlessly decapitated seven captives and rode out to battle in chain mail after tossing the severed heads out into the enemy forces.
Catalina de Erauso served in Chile disguised as a man, and became the subject of some (probably exaggerated) legends of her exploits, all of which depict her as a skilled cavalrywoman.
Such cases were quite rare, admittedly, and the general pattern seems to be (1) cavalry, (2) in armor, and (3) with special dispensation coming from a relationship to a high-ranking officer (de Erauso is the exception to the last). Naturally, there were also non-military female personnel performing essential functions as guides and translators.
It's a little hard to figure out how to represent this situation in a game. A logical way to represent women as symbolic leaders but not frontline fighters would be to alter their statistics by reducing Endurance (the all-purpose physical stat in
FF) and increasing Charisma. This is more or less the same thing done in 1e D&D, which prompted all sorts of outrage based on the recognition that Charisma was an unimportant dump-stat. In a larger-scale wargame, however, the situation is very much reversed, and the value of an officer is based more on leadership and less on personal prowess. It doesn't feel authentic to make women universally better at command then men.
I think the better approach is to design a rule that results in female expedition members being
used in a roughly historical manner, deployed in armor on horseback at the front of the line to
shame inspire men into following them. My idea is to allow them greater mobility as armored riders, with the justification that most women are rather lighter than the average man. Even if that isn't quite true, it still shifts them into a role that feels reasonable and doesn't represent a complete betrayal of history.