This thing looks like a tire scraper/cleaner, but I'll defer to the more knowledgeable Italiophiles. The "newer" Tire Savers serve a similar purpose--cleaning debris off the tire before it makes another pass against the road surface, hopefully preventing punctures.
> Hello. Please pardon my ignorance, but would somebody please explain the
> function of the part attached to the rear brake mount bolt seen in the
> picture linked below?
> I have never this on another bicycle before.
> Matthew Bowne
> Brooklyn, New York