Okay, yesterday was my wife's day off, which meant that my spare time was spent with her(I'm a great husband, dammit) but tonight I can put some serious work into this. Right now I work the middle of the day, so I should be able to get on around five, Eastern time, just so you folks know. 

So my thought was this(and I'd love opinions and possible edit suggestions):

Thirty points to assign(Ascendants get 25) and they can divide them however you want between the two elements of your Realm. I will come up with a skill tree, which you will get to put points into whenever I choose to assign them(probably I will assign them for everyone at the same time). The skill tree will have abilities that aren't literal interpretations of the element in question. You will have control of your literal element from the get go, and your power and skill with controlling it will go up automatically as you "level up" in proportion to how many points you put into it in the beginning.
The skill tree, I think, will be divided into the two separate elements, and a third route for both combined. 

The numbers aren't for any math, they're just for direct comparison(you have fifteen points in Earth? Well I put twenty, so my earth control is stronger). 

I'm trying to think of how the Raiment points will affect your skill tree. The only thing I can say for sure is that if you have your character geared completely to one element, you will not have any access to skills from the other, or mixed skills.