The problem with "easy" rep is that it doesn't
really help you. If you level up using weapons, you're gaining HP along the way too. Besides that, I don't think it's any faster to level using quests (I know it's actually slower for me).
But anyway, at level 15 here's where you'd have found me:
Fort Charles for cutlass, doll, and dagger.
Misty Mire for pistol.