If I did it, I would take weapon placement into account.
You would need to add an AR code (or change in-game) the range/location of the book attacks such that they're further out. Then basically all the opening 'book' sprites just become spear tips.
Also, Astarte would be a very weird fight, as she would target John but not Eric. O_o;
Doing a Marth/Roy one is easier as Roy can use a short sword while Marth would use a long sword. Or if one needed to have range, it'd be Ike and Marth since Ike has a ridiculous sword.