The Dragon Shield is a mystical shield that is part of the complete Dragon Armor. When united with the rest of the armor, it can supposedly control the Firstbourne. It was once worn by the First Spinjitzu Master, before he left the First Realm. It was located in Firstbourne's Nest, until it was found by the Iron Baron and Wu, and the latter now uses it.
When Iron Baron and Wu made it to the nest, he stole the armor and tried to control the Firstbourne. However, Wu told him that it was not the armor that controls her. She promptly buries him in molten rock. Wu then took possession of the Armor.
Wu utilizes the Dragon Shield during his fight with Garmadon.