Quest giver: Caxton
Find an Idol for Caxton
You can bring a Gold, Silver, Bronze or Cursed Idol to Caxton. The quality of his inventory upgrade will depend on the quality of the idol you bring him. The Gold Idol is the best reward you can get by completing the quest Escort Duty
and raising Symone's affinity to max.
The Silver Idol is a reward for completing "Put an Eye Out" notice board quest (Pawn Guild)
A Bronze Idol can be acquired from the Dragonforged's cave in Hillfigure Noll and the Witch's hut in Witchwood
You can give him a forged idol but don't expect any good results.