Make sure whenever you go into labor and are admitted, that the labor nurses that are taking care of you are TOLD right away, that your husband is a light-weight when it comes to blood and other medical stuff. It can help them know that an extra pair of hands might be needed. He wouldn't be the first husband to pass out cold on the floor---but if you know it is a possibility it would be nice to share that info with the people tasked with your care, since they are supposed to be caring for YOU, and your husband passing out will take someone from your care to move him out of the way, etc.
Yes, instruct him to stand up near your head and look at you and hold your hand. He really won't see much there, unless the doc/nurses make a point to show him something. And here again, is where it matters that you TELL THEM not to do that. If they would like to offer to show him, fine, but do not just show.
He might be surprised in that he may handle it all very well. For some people, the amazing experience of watching life coming into the world is just, magical. And trumps any of the other reactions they might otherwise have. You just never know.
If you have any friends who can come sit at the hospital when the time comes, it might be helpful. Then, if husband should become faint, he would have someone to sit with in the waiting area. And maybe someone else could come in to hold your hand if he was unable to stay.
I would also see if you can google birth prep classes online. You might be able to find some videos that are free, that have good information. There is a youtube for just about anything these days....