Idol Worship | Act II - side quests Dragon's Dogma Guide

In short: The merchant Caxton from Gran Sore promises better to sell better items in exchange for one of a few idols. You can give him only one, so make sure you find the best one possible:

• Cursed Idol - outside The Abbey (the monastery west of Gran Soren) - the smallest improvement in the quality of items.
• Bronze Idol - in The Dragonforged cave (Hillfigure Knoll) and it the witch's hut in Witchwood - medium quality improvement.
• Silver Idol - given as a reward for the Put the Eye Out quest, available at the Pawn Guold Notice Board (Gran Soren)
• Gold Idol - the reward for the Escort Duty quest.

In practise, giving the idol to Caxton pays off if you have a damage dealing character (male). Otherwise, the Gold Idol or a different one should go to Madeleine.