I was in a cave with bandits, killed my way to the chief, started to fight him with swords, he jumped forward put his 2 handed sword behind my neck pulled me in and head butted me like he was a woodpecker, I was dead in seconds.

Standard two-hander kill move. Came with 1.5 I think. You'll see it a lot of you play 2H yourself.

Recently played the CW quest. Finished killing all the Legion in Whiterun, at which point all the attacking troops turned to town guards, and started wondering around the corpses from the battle asking: "What happened here then?"

Or if you have a follower who uses 2H weapons. I've caught Erik the Slayer doing this one a lot since 1.5 came about...and let me tell you, it looks really silly when you see an NPC do it.

I had just completed the Civil War (on the Stormcloak side) and was leaving a newly-taken Solitude. Rounding the corner by the stables, I hear the sounds of a fight.
Whom should I see, but Ulfric Stormcloak himself, taking a knee at the hands of a Solitude Guard. I guess the self-proclaimed High King of Skyrim isn't so tough after all.
Being a good soldier, I rush to his defense, only to get tagged with a 40 Septim bounty.
Ulfric gets up and continues his leisurely stroll (back to Windhelm, I guess?)