The fighter archetype "weapon expert" available at level 12 is great if you're a low-proficiency class, but for rogues, a lot of clerics, rangers... it is a wasted feat. Clerics get expert with criticals in their deities favored weapon at 14, rogues get this at 13 (no criticals), and so on.
I'd suggest making this feat improve your proficiency with weapons in that group by one step (to a maximum of master). *Possibly* also giving out critical specializations for all weapons you have master proficiency in. This would make the feat equally valuable to pretty much all the classes, rather than being useless to other martials.
