The Heritage Daja Bow is an unique weapon, belonging to Kadan Bahadur Khan, the Monarch of the D'Shar Principalities. Its a top bow, being stronger than the rare to see and feared Noldor Composite Bow.
The Heritage Daja Bow is considered one of the most powerful bows in the game, being on par with the Duskfall, and the rare runic gem weapons.
To obtain this weapon you need to successfully defeat and capture the king of The D'Shar Principalities (Kadan Bahadur Khan). Once this is done, engage on a conversation with him. If his kingdom has 6 or less castles+cities left, he will have a special option in which he trades his unique weapon for his freedom. This will remove the weapon from his inventory meaning the next time you'll meet him, he will use his secondary bow.
This can only be done if the player is a Monarch.
Note: Since 3.9, Accuracy was lowered from 98 to 95.