[Kairi had just been carefully listen to this whole thing,taking in all the information.]

While we do know about the keyblade exsistance, we only know so much about them to begin with. Also adding to what Ventus said if the power doesn't accept you, then how can one actually learn anything about it except for the people who wield one?

[It seemsed like a logical question at the time, if one couldn't touch one, how was one to learn about it?]

So, I think until then, the defense system would seem to be the best bet, that's all we can honestly do to deal with the Heartless for the meantime