I read a book way back in the 70's/80's. Been looking for it for a few years, it boils down to:
In the future Earth maintains an iron grip on its colonies around other stars. It does so with a variety of weapons including a "hellbore" that can dig down to a planets core and destroy it. There is a rebellion against it, and Earth has a method for creating special soldiers that are surgically rebuilt with a "mesh" or "grid" inside their bodies that lets them turn into "ghostlike" beings that can easily defeat normal humans. The process is radical and kills most humans who go through it.
The Hero is one such soldier who falls in love with his trainer, a woman who I can't exactly remember but seems to be connected with a powerful parent. The Hero goes rogue and I remember him landing on some planet at one point to get in touch with the rebellion.
There is also mention at one point of a space system of mining ore that shoots the ore toward a refining center, forming highways of such deliveries.
I really want to find it but don't know where to start, it's been a long time.