One of the problems I faced when trying to find a system that would fit with what I believe are the desires of both my potential pool of players and myself is the limitations of class in a fantasy rpg. I looked over probably a dozen and even White Wolf's fantasy ish Exalted still has classes more or less. I don't mind playing a character class and most of us have been playing so long we've probably each played them all and can find ways to spice them up. I mean recently in our now on hold Pathfinder game I made a cleric who's obviously capable of healing the party but would rather be doing other things, like unearthing weird and eldritch secrets and stuff. System wise she's like every other cleric. Conceptually she's not. But I'm still stuck being the party's healbot because that's the way a cleric in 3e is ultimately designed. I realized yesterday when I was looking through the cleric spell list designing the weird domain system for my game and discovered perhaps for the first time just how truly boring it is. Granted, there's the occasional gem like Storm of Vengeance which I once used to devastate the necromancer city outside the Tomb of Horrors in Return to the Tomb, but the list is largely healing/damage or buff/debuff spells. I want to be able to do crazy weird miracles, not just bop orcs with my mace while I heal the guys doing the really cool stuff.
There is a point to all that, and I'm not sure I adequately resolved those issues I have with that sort of character but at the least there's less limitation in my game as to what a priest sort of character can do since there's no classes to dictate their skills and such. What I ended up doing was substituting the 'Legend' trait from Scion (which I'm using a lot of stuff from anyway) with a trait called Piety, which like Legend, can't just be purchased with XP in our group. You have to earn it. A crappy priest is probably not going to get beyond being able to perform a few minor miracles here and there. They spell level is going to be determined by how much the player really puts into being a priest instead. Their choice of spells is going to be limited compared to arcane magic users but that's kind of the point. They're not just run of the mill spellcasters; they're performing miracles powered by their patron of choice. Most priests in the game world I'm creating can't do that at all. But, I'm really interested in seeing divine (or otherwise) power be separate from 'level'. It may end up being moot and no one will choose to play one. Magical healing works a little different in Scion and Mage anyway since you can only get any benefit from magical healing once a day anyway. The players are going to have to mentally shift gears and consider more how they approach combat since it has the potential to be fairly lethal in that way.
Domain wise things are shaping up to look a lot like the various iterations of d&d domains, but I suppose that's in part because that's the way that I think of them, having played in those systems for so long and most others have been shaped in a similar fashion.
These are straight out of the Scion Boons with only a few changes. Death in Scion is kind of weird so I separated it out into 2 domains (Dead and Spirit) then filled in the blanks.
Animal, Chaos, Darkness, Spirit, Death, Earth, Fertility, Fire, Protection, Health, Justice, Moon, Psychopomp, Sky, Sun, War, Water, Domination, Mystery, Prophesy, Destruction
I still have to finish these ones, which came from a couple of different sources.
Charm, Corruption, Luck, Madness, Strength, Wisdom, Order, Weather, Blood