He dropped a few notches when he was so mean spirited about whacking Adriana. I would have thought he would show a hint of regret about having to do it. I don't recall him ever committing a violent act in the series before.
They always had subtle hints that Silvio is the baddest of the bad (his last name is Dante - the Italian expert on hell.) He's made comments to Paulie that have stopped him in his tracks. He just shoots people looks and they cringe.
I think, in the end of the series, Silvo's going to have a big part in the wrap up. Something big, like killing Tony.
Silvio was violent before. I think it was the third season. Ralphie's stripper girlfriend (the one he later killed) was at Ralphie's house when she was supposed to be working at the Bing. Silvio showed up, dragged her out of the house, smacked her around pretty good, and threw her into the car to go to the club.
by the way, I'm frankiep, and I'm a Soprano's addict.