The function of a banner is not only ornamental, not even that is its first function. The first Roman banners at the beginning of the republic consisted only of a bunch of wheat ears tied to the end of a pole or spear.
From that beginning, the banners or badges were used so that the soldiers knew their place in the battlefield and different movements with these badges served to indicate also different actions to the troop, therefore, together with trumpets, flutes, bagpipes, etc., the badges were really a system of transmissions.
Later on, a symbolic character was added that represented the honor of the tribe, of the country and of the unit itself.
Character that has arrived until our days.
This toy soldier represents an aquilifer. The most important emblem of the legions organized by Mario Key. The honor of the legion was embodied in its eagle and the loss of the banner was the greatest affront a legion could suffer.