Just to start...let's take a swing at 1st level Arcane Spells:
That's pretty interesting steeldragons.
I wasn't sure whether people had (or would) go for the 9 axis or not. In some ways I can see it being sort of restrictive to do the combined good-evil/lawful-chaos on a spell; just slapping either one or the other would probably be "easier".
I also wasn't sure really if a school would entirely go with an alignment or even mostly.
If it does/would, then the idea becomes much less interesting I think.
As you say, this is probably not a viable game/campaign distinction...unless you were playing a in world of filled with severely rigid moral/ethical societal laws...
But, it sounds like an interesting challenge.
See, this sort of thing pops up pretty quick when dealing with the alignment system in D&D. Always arguments about how strict/not-strict it is, people looking for corner cases, etc.
The thing is... the game treats it pretty rigidly. Not as rigidly as it _could_, but rigid enough. You've got spells that definitely identify good/evil. Sure, you can start waffling around and try and go all grey-area, but the underlying idea is that good and evil can be quantified/measured and determined. A class with alignment restrictions _will_ lose their powers if their alignment shifts.
Now, you can claim it's not the alignment shifting that causes a class to lose it's powers, but instead the alignment shift is merely measuring the character's drift away from the ideas that help power/fuel their abilities... but I don't buy it. Yeah, you _can_ make that arguement, but I don't find it _more_ valid than the idea that alignment is a measurable/active force in the D&D setting.
Aren't planes aligned? And of course there's still the issue of "it's an evil creature, so it's not murder."
Anyway... yeah. I'll have to think about it a bit more I guess. The fact that most of a school matches up to one of the 9 alignments makes it less interesting to me. Although it might be more interesting if magic was simply broken along the 6 alignment axis as the default. Then, you could have certain spells only available to those that specialised (narrowed down into the 9 axis system).
So as a rough idea if you wanted to keep Arcane and Divine separate, then you go with the obvious: Arcane gets the Lawful/Chaotic split, and Divine gets the Good/Evil; naturally, if you wanted to play around with some of the assumptions of divinity (ala Moorcock) then divine could be Lawful/Chaos and Arcane gets the Good/Evil. Either of those automatically sort of say something about the setting.
After a certain point a caster can choose to specialise. Once they do, they get access to certain other spells that are only allowed to that alignment. If you don't specialise, then you just continue as you have been.
Or again, if you want to make a statement about the setting, perhaps spell levels themselves are capped if you're not completely aligned. So for example, say the cap starts at 6 level. An Arcane caster can learn up to and including level 5 spells. Beyond that though, all they get is more spell slots; you could probably burn those slots for various metamagic feats, but whatever.
If they want access to 6th level spells, they've got to switch from the 3 axis to the 9 axis. Depending on the statement you're making, the 9 axis could simply be a "gatekeeper" in that you can pick _any_ of the 6th level+ spells, or it could be restrictive and only allow 6th level+ spells that also match the particular alignment you've selected.
Alignment then becomes not just a measure of how a person interacts with the world, but is even an actual measure of power. Some dude busting out "Mage's Sword" is A) Powerful and B) Particularly driven, because they've dedicated themselves so completely to a particular ethos.
In other words, alignment actually becomes a serious thing within the world. Not everyone is going to register on the battlefield, but those that do... look out.
Again, tapping Moorcock... there's a pretty serious difference between Elric and Conan. One of the differences being the role that alignment effectively plays in the setting; in Conan, it's pretty much the "standard" that you see in D&D games, but in Elric... alignment is alive and actively waging a war.
Hmmm. It's only as I've been typing this out that I've started to have some of these ideas gel a bit. I'll have to think about it some more and see where (if anywhere) they take me.
Thanks for your input man.