i did a limited version of this in my last campaign.
to distinguish between different cultures of each race, sometimes i'd allow a culture to treat a specific exotic weapon as a martial weapon.
there was a dwarvish culture that had the urgrosh as a martial weapon, a halfling culture that treated the halfling skiprock (from S&F) as martial, and a gnoll culture that had the two-bladed sword as a martial weapon.
i didn't bother to totally remake the simple/martial/exotic lists for each culture, but that is definitely a possibility if you want to accentuate the differences between regions or cultures.
hey, here's a simple way to implement it: if you are using the idea of regional or cultural feats like in the FRCS, you could put in an EWP as one of the region's feats. it doesn't give anyone in the region the weapon for free, but it suggests that there will be a higher percentage of people than normal that know how to use it.