HUH? Sorry, don't understand.
If your horse is leaning on your hand or getting heavy, it is because he is heavy on the forehand and he is using YOU for his balance. A horse CANNOT be light and lean on your hands at the same time. He will never be able to engage his haunch while this is going on. He needs to be driven forward, while working on lightening the forehand.
You never want to lighten a horse with a harsher bit, IMO. You will only teach him to be afraid of moving forward into the bridle and carry himself for fear of the bit's "bite". But that is my opinion.
I also agree with the rest of your post :)