I couldn't find references about the action type(s) of the following acts (standard, move, full-round, etc.) nor if they provoke attacks of opportunity.
- Retrieving an item attached to the character's equipment (such as a pan hanging from a hook on the backpack).
- Retrieving an item in the main sack of the backpack.
Is this one of the case-by-case things left to the GM's discretion?
How would you model them in their commonest case?
Best Answer
In D&D 3.5, it would indeed be a move action in the general case:
http://www.d20srd.org/srd/combat/actionsInCombat.htm#manipulateanItem
Checking the Pathfinder SRD at d20pfsrd.com shows that retrieving an item is still a move action in Pathfinder:
http://www.d20pfsrd.com/gamemastering/combat#TOC-Actions-In-Combat
For the frying pan, you might rule that it's easy enough to grab on to that it behaves like a Handy Haversack, or drawing a weapon. In that case, it would still be a move action but would not provoke attacks of opportunity: