You can get an [Event] Frosted Matchlock either by completing the series of quests listed below in the chart or by looting Piku. However, the grade and stats of the [Event] Frosted Matchlock you get through the event quest and the one you get from looting Piku are different. Also, the [Event] Frosted Matchlock you get through the event quests will be deleted after the event concludes, during the January 8 maintenance. The one you loot from Piku will not be deleted.