As for exactly how to implement the subset specialization, I thought it would be really cool if SE used something similar to the License Board from FFXII. Here's a couple images I made with Photoshop of what it could possibly look like:
http://img.photobucket.com/albums/v2...haumaturge.png

http://img.photobucket.com/albums/v2...rdConjurer.png
I think this would be a great idea I loved it in 12.