[Drax]

it can be a standard, it can be a backpack banner, it can be in the form of a flag, a metal symbol, it could be bones like those in the SoB's Simulcrum Imperialis - for chaos it tends to be the metal symbol, but that doesn't mean it must be.

as long as it is clear that something represents the icon, it can take whatever form you like - i suggested to someone a while ago that they use the shield from the Slaanesh Lord on steed of slaanesh from the fantasy range for a Slaanesh icon, as it has the O-I-C symbol, but could conceivably stretch to count as a hand weapon.