An off-hand dragon crossbow is a crossbow similar to the Dragon crossbow except that it is equipped in the offhand slot. It requires a Ranged level of 60 to wield, can use bolts up to Dragon. It can be made with a Fletching level of 94 by using a crossbow string on a dragon c'bow (u), granting 100 experience. Once the crossbow was untradeable, essentially binding it to the player who made it. However, in a hidden update on 14 January 2013 the crossbow and its variants became tradeable at a starting price of 14 million GP.
Note - This does NOT work when making ascension crossbows. It comes up with a declining message from Ocellus.