The off-hand black crossbow is an off-hand crossbow that is more accurate than a off-hand steel crossbow. It is members only, and requires a Ranged level of at least 25 to wield. Black crossbows are a possible reward from level 1 Treasure Trails, but unlike most crossbows, they cannot be made using the Fletching skill.
Both black crossbows have tier 33 accuracy, but cannot exceed tier 25 damage.