What to do about a coin with no luster, but also no wear?

In simple terms, the dies do. And no, it's not because Morgan dies were bowl shaped, as not all of them are, only a few were. And yet the difference still exist in all.

The thing that makes the difference is the preparation of the surface of the dies. The simplest and easiest way to understand this, and see examples of it, is for one to look at matte finish, satin finish, brilliant finish, and mirror finish. Each and every one is different from all of the others. And yet nothing is done except to change to what extent the dies are polished. The method of polishing remains the same, it's merely the extent that changes.

And it goes further than the difference between Morgans and Peace dollars, and beyond matte, satin, brilliant, and mirror - every coin type there is has its own type of luster. And each and every one of them is different, at least slightly, than all others.