My issue with EWP Bow is that it permits you to alternate between what is basically a club attack to a ranged attack every round. That's rather potent in itself. You may consider either (A) scaling the damage to account for the Archer's ability to do so or (B) hold it until 5th Level or so at the current damage.
Also, if Sovereign Stone does have a precident class (Thanks, Earth's Shadow!), you may want to review it as suggested.