Much like the mane 6 with their elements of harmony, rockhoof's shovel and the other Piller's items are just tools, they were not meant to be their source of strength and power to begin with, all that Rockhoof and others need is themselves to believe in what they can really do, that's why he returns to buffed up self at that point when the epic concussion happened near the end there, when twilight focus all that friendship power from the pillers, young 6 and mane 6 onto the mean 3, to strip them of that power that didn't belong to them in the first place.