We might be jumping the gun, as we don't have full information on this PrC. That being said, what happens to a Fighter who dips into three levels?
He uses 3 EWP, probably only one of which is useful. There's enough similarity between an Urgosh, a Dire Flail and an Orcish Double Axe, most characters won't get any two of them.
The other categories of EWP's are the spiked chain (reach + close), ranged, and a few miscellaneous ones (kukri, monk weapons).
I suppose it's conceivable for a Fighter to take EWP: Shuriken, EWP: Dire Flail and maybe Spiked Chain, or some similar combination that isn't a batch of completely "wasted" overlapping weapons, or are weapons that have little usefulness. For instance, a kukri isn't that much better than a dagger except in some circumstances. A hand crossbow is a sub-par choice, as is the repeating crossbow. Shuriken are really only good for weak characters to use as a poison delivery system... and so on. The "miscellaneous" EWF tend to be sub-par "flavor" choices.
Overall, I'd label that as 1-2 wasted feats, not three.
In exchange, the Exotic Weapon Master gets numerous EWF's at first level, then numerous weapon focuses, then numerous weapon specializations. Mostly these are redundant, since you aren't going to be carrying seven or eight weapons. It'll only be really helpful if the treasure haul happens to have a +n Magic Halfling kama and the party has no one else capable of using it well. Essentially that comes across as a bonus of 2-4 feats.
A fighter gives up 3 levels and 1-2 feats to gain 2-4 feats. His net gain is 3 feats, or 1-2 more than he normally gets. It's a nice class for Fighters, but not a game breaker, I don't think.
Now if the requirements would include the virtual feats of a Monk (monk weapons), a Rogue (hand crossbow), or a Bard (whip), then it becomes a whole new scenario as these characters don't have nearly as many feats and gaining access to a bunch of bonus feats, one of which is Specialization that they normally can't get, that's quite a lot more powerful. I'm thinking specifically of a Monk/Exotic Weapon Master/Weapon Master (Lajatang). That'd be beefy, but hard to get. A more reasonable goal might be Ranger/Exotic Weapon Master/Master of Chains. Ooooh. Sounds crunchy.
I think I'll wait to pass judgement but the Prc still sounds powerful, though not as powerful as the surface facts make them seem.
I hope that provided some food for thought,
Greg