One of the superheroes in my mental roster is a former villain who was possessed by a cursed sword, and spent the next few years being its puppet. But when the curse was broken, she discovered she still had the muscle memory for expert swordplay, and as long as she wasn’t consciously trying to use it, she was amazing with any sword she picked up.
There might be a training montage we haven’t seen, where William teaches Adam and Jordan swordplay while on the Love Bug. Take a shot at it if you feel up to it, visually or otherwise 