Gratnuk gromril is saved for the most dangerous of jobs, ie for the Ironbreakers who will have to check out any skaven tunnels etc and fight them. The miners work in nice safe dwarven made mines (not like those shoddy rat tunnels....), and have all the protection they need.

The magic standard will make them a bit powerful and also if they get lost then what? all those pts for nothing.

I think they should have the ICFB rule but recently it's been brought to my attention this may make them a bit powerful, so I might have to rethink about them.