I like how a lot of these function, though I have issue with the Expertise crystals, given you can't use the Greater crystals unless your exotic weapon is already +3 and not every bec de corbin out there that you want to use is going to be a +3 whatever one.

I know what you're trying to go for here with the different tiers of equipment but I think I'd move to make them just one crystal of least power so that any weapon or armor you care to plug it into only needs to be masterwork to use properly. Still not exactly perfect but more on a parallel with the Skillful weapon special ability and all around more user friendly.