Hmm well there is another human human fruit called the human human model: Daibutsu which gives the user extreme size expansion capabilities even though its inspired from some religious monk statue? That isnt even human,if a human eats the human human fruit I say either one of these 3 things will happen:1.) Gain the ability to manipulate size but not have the whole golden aura thingie
2.)Gain a vast amount of brain power and probably be the smartest thing in the world (slightly leaning towards this as human beings only use 10% of their brain and eating the human human might allow them to use 100%)
3.)The "illuminated" part maybe they'll just know some secret behind the meaning of life and always be happy or look at the bright side even if the situation is bad