I took the Shield Power Bashing perk and its so useful cause by just pressing both the right and left mouse button at the same time, I can hit an enemy very hard with my shield, while at the same time protecting myself.
This is one of the reasons why I think sword + shield is much better than duel-handed or duel-wielding.
If you attack while blocking, you get the same effect.. Same with torchers, when you block with a torch, then press the attack button, you light enemies on fire..