Nooseph - conveniently, I was as well recently thinking about the possible complication that St. Joan of arc presents and that you described(joan being an ace in the hole for feminists). But, as I read about her life the other day, I don't think so, and I think she is quite amazing. It is somewhat mysterious, and likely way over the head of feminists and beyond the scope of this keyboard. But, the "math" does add up imo concerning St. Joan.
And, if anyone digs a bit deeper, they will find that St. Joan is not promoting what we see going on in modern female society.
I suggest that you thoroughly familiarize yourself with St. Joan(buy the authoritative/traditional text(s) on her life) and when that conversation comes up with feminists, you can in all charity accurately explain who she was and why she is exalted by God. I think you ought to develop a devotion to St. Joan in order to strengthen your arguments. Because, I don't disagree with them, and I don't think St. Joan would either. Remember, she did all of this because of supernatural visions. If the visions had not been, she would have been at home spinning if I recall correctly.