Originally Posted by
voidspark
Force and verve and attenuation are definitely not armor mitigated, whatsoever. That said I know there's definitely some stuff where the armor helps and obviously if stats are similar (even ignoring the armor, the shield should be better than the OH from heroic mode), you'll want the shield.
Personally on my paladin I made a 476 offhand with better stats, because the damage on Vizier is not armor mitigated, but in case a shield would be helpful on other fights I kept my 471 shield in my inventory. Can't go wrong that way.