Been playing the game for well over 1000 hours and never saw this before. In Dustman's Cairn walking down a hall and two Silver Hands see us. One charges and the other draws his bow. Farkas charges the one charging him. Farkas then does a forward roll and cuts down his opponent. He did it one other time versus a draugr wight. It was super cool and I want to know how to do it. Is it only for two handed swords? Anyone else see this? Anyone do this? If so, how do you do it?

It's called "Silent roll" in the Sneak-tree.