So, I don’t know how helpful my comment will be on this thread, as very good answers have already been presented. But I’ll give it a shot.
My MC, Baroness Kyreleis, is a very atypical main character without even considering that she’s a woman of power in medieval Europe (look up Matilda of Tuscany for her much more moral real-life counterpart). For one, she’s not a very good-hearted person, even by the brutal standards of a Europe at war. She’s totally ruthless, and wouldn’t even blink an eye at enslaving or sacking a town to advance her personal wealth and power. Her redeeming qualities are primarily in her strict adherence to her personal code of honor and her (generally speaking) integrity and loyalty to family and oaths made in blood. As a military and political leader who is the ruler in her own right and not as a lord’s wife, she is by necessity required to embody masculine attributes to maintain her authority over her soldiers and subjects – to assure her soldiers that she is capable of leading them in battle, she has to don armor and fight with them, and to keep her political enemies at bay she cannot afford to be overly gentle or meek.
Part of what makes her feminine (I hope!) and not just a man with lady parts is that she in some measure resents this role, even if she has come to thrill at conflict and battle. This was not how she would have wanted her life if she’d had a choice in it from the beginning. As much as she is a warrior and statesman, most of her scant personal time is spent brooding on unresolved questions of morality, justice, the conflicts she must face, and her unfulfilled desires. And while she is a ‘strong’ female character, she doesn’t resent men for being men, and she’s not just a voice of feminism in the medieval era; she accepts that she is an abnormality, and she didn’t want this authority in the first place. And while she is a skilled warrior, she acknowledges there are knights who are far better than her – she is a leader first, and a fighter second.
I don’t know necessarily how helpful this was, but I suppose this is my conclusion:
By nature, a female character who is known primarily for fighting is going to embody some masculine traits as a result of their occupation. But rather than simply glop on some happy girly things to balance the gender arithmetic, I would spend time meditating on how she got into this role of fighting for a living, why she fights, and how she copes with the stress of said constant conflict (men are physiologically adapted to be the hunters and warriors, and even we do not hold up particularly well under constant conflict. Also bear in the mind the culture of the world you’re writing in: in the West today, war is a horrifying experience that scars those who participate in it, but in the warrior cultures of antiquity, when battle was fought face to face in gruesome fashion, we do not have accounts of anything resembling modern PTSD – and they also did not value life nearly so much as we do nowadays.)
That went on too long. 😛
Non nobis Domine, sed nomini, Tuo da gloriam.