Okay, I've been working a long while with some friends on a persistent campaign world. Long story short, one of the guys that has been working on a unified theory of magic for it.
With the addition of Words of Power (which we like, and will be using, for sure) some questions were raised on how to fit things in flavor wise along with mechanically.
Even in Ultimate Magic, it seems like the flavor of the words of power is that they are more primal and based on the nature of magic. This is the way we're going to be treating them as well.
The world does have a difference in divine and arcane magic, and that seems to be preserved by word lists for different classes. I've posited that there is an inherent difference in harnessing the energy of divine/mortal magic, and that is why even the high level theurges can only used them together or interchangeably to a small extent.
For many classes, "learning" and "casting" are the mechanical dividing point for the world. The reason a separate spell-lists exist for a Wizard/Sorcerer is because some are learned, others are inherent. Most of this is addressed mechanically in a "spontaneous v. prepared caster learning curve".
Mechanically, I know there is a balance reason for wordcasters to have seperate word-lists when multiclassing. However, I have a player insistent on playing a Bard/Sorc- both spontaneous, arcane casters. For flavor, how can these separated? Mechanically, what kind of problems would there be if when "learning" words a word that is on both lists is learned for both classes and can be used on either spell slot?
E.g.- upon gaining his 3rd level, he learns the time word "dash", which can be used in his bard spells or his sorcerer spells since it is learnable by both classes.
