I have no experience rod building so bear with me. The rear handle on my rod completely separated from the blank and the reel seat. It is still attached to the butt of the rod but the front end moves around. I have tried super gluing/epoxying the handle to the reel seat but after a few hours of fishing the connection breaks and the handle is loose again. Here's a picture so you can see what I mean. Any ideas?

 

Split grip, or whole grip?

I gather from your initial post that the seat is what is moving relative to the blank, right?  The way to fix it is to get epoxy between the blank and the seat.  Gluing the two parts together in that slit between them isn't ever going to work.  If the rear grip is loose, the fix is the same.  Inject epoxy into the space between the loose part and the blank, force the loose part into proper position, and hold it there with rubber bands or clamps or some cobbled up method that you design and test before you start.

 

To do the fix drill two or three holes carefully through the loose part and to, but not through the blank.  Then inject adhesive epoxy into the holes.  You want to get holes that are 1/8 inch diameter or so, and you want a syringe that will fit to those holes and allow you to build up substantial injection pressure.  Inject quite a bit of epoxy; you want to get a large area wetted with it.  If it's unclear, please respond.

 

Big box rods, believe it or not, often use cardboard shims between the seat and the blank, they get wet and lose their integrity.  

What tools do you have handy, can't help till I know what we're working with. You already said you have nothing to rotate the rod on, correct? Looks like shrink wrap over cork or eva.