This trophy is obtained for completion of the second main story mission and is thus unmissable part of the progression through the game.
**Quest Spoilers Follow**
The second main story mission will start when you are requested to an audience with the Princess in the Castle upon completion of the previous mission. At the Castle, the Prime Minister will inform you that the royal scepter has bee stolen by a thief (Tommit) and directs you to recover it. Rammi directs you to the 'Old Capital' (dungeon level 2). Proceed through the Old Capital and you will shortly meet up with Tommit who will run away from you. Proceed through the level and eventually you will fight the boss (Wyvern Leader). Upon defeating the boss you will receive the royal scepter, but you will need to return it to the Castle to get the trophy. Walk into the castle, select the first option in the cutscene (you cannot proceed until you do) and the mission will be complete and the trophy will be awarded to you.