Speaking on medieval military slinging only, you'd occasionally see women as slingers when a city was besieged (no direct slinging depictions I know of, but here's a one of a woman chucking a rock:
https://manuscriptminiatures.com/4832/7940 ), or a ship was under attack (we have a record of Barbora of Svaty Jur who captained a galley during Sigismund's Nicopolis crusade and was rewarded with land for it), but that's about it. At least officially.
There probably were a scant few women in various mercenary companies under some kind of a vague don't ask - don't tell principle, but that firstly depended on the captain in question and secondly, there are absolutely no records one way or another, so meaningful discussion is not really possible.
As for civilian and self defence use, sure, as many as there were men, or maybe slightly fewer. If a medieval monk can teach a woman how to fight with sword and buckler...