Once an account-bound item is picked up, it cannot be given to a character belonging to another player. The item cannot be traded to another player, picked up by another player’s character if dropped, or placed in a Guild Stash. The item can be placed in a player’s regular stash, where it may be accessed by the player’s other characters within the same league. An account-bound item can be recognized by text in its infobox that reads "Account-bound".
Previously, relics and sanctified relics were account-bound. Relics were made tradeable in version 3.22.0.