"I would be tempted to introduce two currencies - mortal and divine fate points. Maybe split refresh between them, but I'll touch on that more in a little bit.
"See, while I would divide the currency, I would not divide the aspects. Since the game is really about that line between mortality and divinity, I would view every aspect with an eye on trying to figure out it's mundane and its mythic resonance. Something like "Bad Temper" is straightforward enough on a mundane level, but on a mythic level it might shake the earth or call storms from the sky or otherwise be something dramatic and destructive. Basically, how would this aspect play out if Odin had it? By the same token, a divine compel is can be more dramatic and metaphorical - it may well be that the character is literally attacked by demons of anger as a compel on his Bad Temper.
"With that understanding, the division in currency hopefully becomes more apparent. How and invocation or a compel plays ties to which currency is used. If the player uses his bad temper to punch a guy, he spends a mortal FP. If he uses it to strike down the bar with furious thunder, he spends a divine FP. Similarly, if his bad temper gets him in trouble with the cops, that might earn a mundane FP, while drawing the attention of one of the Furies might earn a divine FP.
"Given that, you get a nice dial on how divine things get and how fast. You could start the game with nothing but mortal FP and introduce divine FP solely through compels, and as the game progresses, you could start splitting the refresh pool of FP between divine & Mortal points, so after a few sessions, players may begin play with 2 divine point and 8 mortal ones. This also has the interesting twist that as the game grows more divine, mortal FP become rarer and it becomes harder to go to the bar for a beer without things being EPIC.
"For artifacts and such, I would be inclined to go for a more abstract system of putting aspects on these items that correlate with their legend. These are pretty much purely divine aspects, but depending on the artifact might allow one or more free tags. That could get fiddly, and it depends a lot on how central you want artifacts to be."
It's a great idea for Scion, obviously, but the concept of having differing flavors of Fate Points can apply to any number of genres. I've heard it (or something similar) proposed for Star Wars games, aka "Spirit of the Force," using Dark Side Points. Acquire more Dark Side Points than Fate Points and bad things happen -- use those Dark Side points and even worse things happen. I've thought about introducing an honor mechanic of some kind into "Spirit of the West" to represent the moralistic determinism of Westerns. There's the sense that some people just have it coming. Infamy Points might just do the trick there: If your Infamy Point total surpasses your Fate Point total, you gain a new Aspect: "Wanted."
(Of course, an Honor Stress track might do the same, so... the quandry persists.)
As for "SotS," it occurred to me in the car this morning that there might not be any need for a Magic skill at all. What if spellcasting were a stunt category of Art? And if artifice fell under Crafting? And hedge magic under Survival? It's a very different take on things, one that posits magic as an extension of daily life and mundane skills. I'm intrigued by the idea -- maybe not enough to implement it now, although I'm not ruling out the possibility. I'm interested in seeing your take on this, too, so fire away.