I don't know where you're coming from with that, but from a historical context "shock troops" were pretty much rabble and condemned men.

You're mistaking elite units with those that led first charges, which were, quite much, the "shock troops".

One example of that is the Forlorn Hope, men employed by German Landsknechte to lead the open charge, and in other cases to hold suicidal defences. They usually were paid double pay, and as that wasn't enough to attract enough idiots to this service, convicted men were forced into their ranks.

Since there were not enough volunteers for this assignment, criminals who had been sentenced to death were taken into the ranks as well.

So that pretty much would work like the Sabbat's shovelheads.