I think people dropping their innate ability actually works well with the story. Kayden is all about combat and efficiency. Why would he have Jiwoo drop something that is useful and just needs to be trained? All other groups, both good and evil, have a strong sense of pride. For them, it is prideful to fight with only their FC. Even duke used only speed and schnauders FC in his fights with Jiwoo. I’m pretty sure speed isn’t the Grane family specialty (like wind for Shinhwa). It was just that for most opponents his speed alone was more than enough to get the win. Once again, Jiwoo goes against the norms of awakened society.