CathInfo.com

Sounds like your reading material is questionable, at best.

As for launching an attack on a Holy Day, there are quite a few on the calendar. You would have a hard time avoiding them while trying to campaign.

Jesus did not violate the Sabbath by doing a good work; even though it scandalized the Pharisees.  

St. Joan was acting on a Divine commission to liberate Paris and France; also a good work, although it required military force since the English would not go quietly.

If she was trying to give battle, why would she not resist capture and arrest by her national and personal enemies?

She was burnt primarily for the alleged crime of heresy. When she refused to deny her mystical experiences and Divine mission, she also returned to her militant male fashion choices.

Since she was on a Divine mission to accomplish things usually done by men, she had to dress accordingly.

She wore armor to protect herself in battle, and she wore male clothes to protect herself from the soldiers guarding her in the English prison, as well as other things like riding into battle. She did not "cross dress" for any perverse, or unseemly reasons.

She was put through four, unjust show trials before she began to falter under the abuse and deception of her enemies. She finally agreed to demands to recant that she did not fully understand; but when she realized her mistake, she renewed her claims and male attire. In the years that followed, her family and the Church cleared her name and later canonized her.