This skill allows the character to place an accurate value on certain in-game items. It will not identify whether those items are magical, but only how much they might fetch on the open market.
This is usually accomplished by consulting an out-of-game list that your chapter will keep. The list will contain the in-game items that have a game number, along with their monetary value. Obviously, items that are not from that chapter will not be on the list, and so a character finding such an item will be perplexed by the material or technique and thus unable to identify its worth.
This skill also allows the character to sell game items (potions, scrolls, alchemical substances, armor, weapons, Channeling Sources, and traps) to Logistics during normal Logistics periods for their Production Point value in game money. Items that are not produced through the Production Point system (components, ritual scrolls, magic items, etc.) cannot be traded in, and must be sold in-game.
If a Production Point item is sold which has had additional crafting performed upon it at a set cost (such as Strengthening or Silvering), a Merchant may regain the additional crafting cost that was originally put into the item.