Collector icon is an item worn in the cape slot while playing Barbarian Assault. It shows that the player is a collector indicated by the yellow circle around them with the collector symbol. It cannot be removed or interacted with in any way besides examining it. When a game of Barbarian Assault finishes, the icon is removed.
Having a higher level in the Collector role, which can be done via Commander Connad or choosing to do so immediately after a game, allows the collection bag to hold more eggs, and an increased chance of success when converting eggs.