Large Blue Rocket

The Large Blue Rocket is a type of firework associated with, but not exclusive to, the Lunar Festival event.

A Firework Launcher is required to use a Large Blue Rocket. (see Notes section)

Source
This item is crafted with Engineering (175); taught by Schematic: Large Blue Rocket.

This item is also contained in the Lunar Festival Fireworks Pack which can be purchased for from  in Moonglade during the Lunar Festival.

Object of
Lunar Fireworks requires that you launch eight Lunar Fireworks (color and size not specified) and two Cluster Fireworks (color and size not specified). Large Blue Rockets are a Lunar Firework, but they are not vended near the area of the quest, so are not a convenient item to use to complete the quest.