The hierarchy of the staff members
As we saw throughout the episode, staff members had a well-defined hierarchy and regulations. The circles, triangles, and squares were in that order at the bottom. When detective Jun-ho slips into the tournament as a circle staff member, he’s scolded by a square for chatting without his supervisor’s permission.
However, even though the squares were on top, they did not have weapons, as the only pink jackets with weapons were the triangles.