>In the book of Magecraft it states that elves use the art of spellsong to cast
>their magic. No race, even half-elves can master this. It doesn't really say
>much else about it, but if you are looking to give elves a slight edge (and
>have precedent for doing so) perhaps you can use this.
>Disclaimer: I have not done this in my campaign. And don't do this for Realm
>Magic, it'll really scew the game balance.
>The edge is this: elves using spellsong do not need spell components. That's
>it. Now make everyone else (priests, too!) use the require spell components
>rule. NOW you've got an advantage. Think on it...

Why not use the rules that exists for spellsong. I admit that they are not made specially for Birthright but I think they might work anyway. It can be found in the Complete Bard's Handbook under the elven Minstrel Kit.