May well have got that detail wrong, but that's the report I saw. I'd certainly contest that the attacks were "unprovoked" after speaking to an Englishman (neutral fan) who was in Liverpool on Tuesday.
I'm actually a huge fan of Italian football and in fact I've been to more Italian games than English over the last couple of years, most of them in the various ultra ends (including the Rome Derby), so I'm well aware of the reputation and history of the various Ultra groups.
I've also been going to football in this country home and away for over 25 years, and could reel off a list of Liverpool fans misdemeanours that would roll off the bottom of the page. Some Liverpool group's behaviour is pretty shocking, and they are no strangers to using weapons.
Sorry to hear about your friend being stabbed.