This is to all photographers that uses a lot of handheld lighting. It's not easy training your assistants to the way you want with handheld lighting. Firstly they must be really into this kind of stuff for them to really go into it and get better at lighting on a boom.
Don't get me wrong, most of the guys I work with are good guys but even after years, I still find often that I have to go in myself and man handle the boom so that I get the light the way I visioned it.
It's true no one knows better than you do to how you want it lit, but unfortunately you'll never get to be your own lighting guy because you like to shoot handheld as well and if your assistant assists you with that then it becomes their photo and not yours.
Talk about tough...