If you vote based on who has the most violent supporters, then you'd be crazy to cast your ballot for a left-winger in any Western country. There's a contingent of far-left protesters in the West that just cause mayhem at any major event, like party conventions, G8 summits, WTO summits, Davos, etc. You barely hear about it because it's basically background-noise to Western society at this point. I don't think it's fair to use this as a shot against everyone on the left, unless they're trying to accuse conservatives of violence, or unless they're purposefully tolerating or equivocating about the violence, like the mayor of San Jose did.
Mr. Berlusconi was also anti-immigrant, similar to Trump (actually not quite as coarse, but no matter). It didn't matter much one way or another, frankly. I get the impression today's Italians don't look quite that fondly on that era.
I get that some of the above (the EU / global part) is part of the reason for things like Berlusconi, Trump, Brexit, etc. I also think, ironically, that any economic impact (which in some cases is big) might disproportionately affect many who vote for such things. Talent / company "brain drains" happened under Berlusconi, and it looks like the same will happen under Brexit. Those that can are more likely to move wherever the jobs and opportunities are. Those that can't end up in a not quite so enriched country. This really isn't a solution for the globalization / technology inequality problem. It might exaggerate it for all I know.
The second: Since 9/11, only two general classifications of terrorists have actually committed mass murder in America. The first is Islamic terrorists. The second is right-wing terrorists (right-wing as in: white supremacists, anti-semitism , militia types, anti-abortion advocates). Don't get me wrong -- the far left-wing certainly is capable of violence, the clashes at the Trump rallies are deplorable, and there have been murderous radical left terrorists in the past. But these days, I consider right-wing white supremacists in particular the most "likely to commit terrorism" category next to radical Islamists. I don't know of a left wing incident recently where a church was mass-shot; white supremacists have mass-shot two churches this decade.
It, of course, is not fair to use these right-wing white supremacists as a generalization of conservatives (as it would be the other way, as you say). But Donald Trump's unashamed nativism, macho authoritarianism, and identity politics does make me worry a bit whether this will encourage more white supremacists terrorism in the future. We'll see, I guess.