Increases the experience gained for each newly discovered Codex entry from 50 to 75.
The belt must be equipped for the effect to be received.
The belt can only be equipped to the Warden, and thus only the Warden receives the benefit. Other party members, however, receive 50 xp in addition to the Warden's xp whenever a codex entry is picked up, regardless of who actually picks it up. If an ally picks up the entry, the '75 xp' marker will float above the Warden's head, even if they are off-camera, and the xp adds accordingly.
The total number of xp-eligible codex entries is around 200, depending on installed DLCs, roughly 2/3 of the total entries in the game. Some may be picked up prior to this accessory's availability at Ostagar and depending on origin, thus even with the accessory equipped for the entirety of the game, the player can reasonably expect no more than ≈4500 additional xp from doing so. Because of this, it is possible that players are better served by not tying up the Warden's belt slot for the duration of the game, as is the case with the Memory Band. The best use of the belt, therefore, is to equip it right before picking up a codex entry and then switching it with the player's preferred belt afterwards and/or leaving it equipped only in codex-heavy areas such as the Circle Tower and Orzammar, until all of the area's entries have been retrieved.