Premier Shield is an emote unlocked by redeeming the code premierclub18 when they visit Diango in Draynor Village using the right-click "redeem-code" feature.
Upon use the player crosses their arms and a shield will appear before them. This emote will cycle between a bronze, silver, and gold shield, referencing the 3, 6, and 12 month packages from the Premier Club.
The emote shares resemblance to the Safety First emote from Runescape 3.
Despite being released in game on the 23rd, the code was not revealed until the next day in a newspost.