Seeing how oda labels fujitora a swordsman, someone who legit never used his sword for slashing/stabbing/cutting/whatever, i'd guess oda probably views big mom as a swordswoman as well.
And also considering oda labeling fuji a swordsman, i heavily doubt that the WSS title is about only swordsmanship, but fighting in general. That would mean mihawk > fuji, mihawk > big mom. If the WSS title is about only swordsmanship, then this isnt necessarily the case. And since zoro is going to be the future WSS and he uses kicks, punches, demonic powers to grow extra heads and limbs, that just adds to why i heavily doubt it is about only swordsmanship.