1) dragon shouts: even shouts, greybeards are able to do dragon shouts its been confirmed. Todd claimed that they are the masters of the voice (shouts).
2) heavy attacks: i saw tiny leaked combat video which shows a simple villager blocks everything that you trow at him (improved AI) and he actully counter attack with charge heavy attack on the player.
3) finishing moves: its been confirmed that enemies can preform finishing moves on you, dunno about monsters doing it but probably humans only.
4) Magic: obviously there are necromancers and evil mages that will attack you with powerful spells and even revive corpses around them to kill you.
5) Archery: in one interview a guy saw an imperial guard shooting and killing a redguard woman from great distance from down hill where he was standing, (again improved A,I)
6) Shields: we saw in E3 demo a bandit in a cave wielding a large shield and blocking your attacks, well that was the only Alpha stage, think how good it will be in the final build.
now the only thing that wasnt mentioned, is can enemies Duel wield like the player?