I'm preety sure "never challenge a swordsmaster to a duel" is right up there with "never bet against a magic user"

Btw that skill Cynthia used is a type of Blademaster ability called "Bushido abilities", which use the AGI state instead of the STR stat. I'll make a list of the ones she knows when I get home, but that one is called "Skylark's Song", and it's a single strike attack adding your AGI stat as a combat bonus.