I am new to Pathfinder but my understanding is that there is a Feat where if your a follower of Iomedae you can choose Longsword as your favored weapons and gain a +2 to hit with said weapon. The downside is that you can never use any other weapon without having to atone. So for instance if you use a bow or a dagger in a fight you would lose the Favored Weapons bonus until you atoned...
...but what about Shield Bash? In all likelihood this too would count as the use of "a non-favored weapon" although I could argue it both ways.
I hope I am wrong but either way - what is the answer?
-H