Some units, of course, become a little worse when upgraded. For example, the ogre mages are clearly too overpowered, as are the death knights and the queen of the nagas. Off the top of my head, another five to seven units could be sent for further refinement. But even in their current state, they don't cause any obvious dissonance.
The military doctrine here is developed only at the level of strategic decisions. Ordinary soldiers continue to go into battle with huge hammers or scythes; this is already a tribute to the atmosphere, a necessity to convey the image. Although if the image has already been conveyed, and they hang all sorts of trinkets on it, it is, of course, disappointing.