No, you can't eat the ball of hands. You are a duck now. You eat breads, bugs, and sometimes unlucky frogs and fishes. Do I have to teach you everything?
One does not simply eat souls willy nilly. You must cultivate the souls you plan to consume first. Also, it's even better to milk souls rather than to consuem them outright. The food source is more sustainable that way. As for flesh and bones, c'mon, those will rot your beak.