Rahmdah is a weaponsmith in the Vehtendi Valley. If you give him the required amount of crafting materials, and pay him a fee in gold, he will craft you one of the weapons from his "menu". Also, for a fee of 10 gold he can customize a weapon for you. This will increase its damage by 20%, but means that no character other than the one it is customized for can use that weapon (or your heroes).