While I would not find myself playing such concept, it does sounds interesting and worthy of exploring. Apart of magic whistles, the player could be rewarded with other magic artifacts that could only be used once per day or per quest. These artifacts could cast spells like: fireball, invisibility, healing, telekinesis (pushing or pulling an object from afar), putting a target into a deep sleep, teleportation, freezing etc. Maybe the whole game could be about the player helping other creatures until he could be accepted by the "highest order of fairies" to run long and harder quests of larger importance.
Another thing you could do is limiting the amount of artifacts the player could carry for each quest he goes in, making the whole thing quite strategic. Some quests could be more about fighting or defeating someone while others could be simply about retrieving an item or simply learning information about something.
