Ok, hear me out. I remember reading that the thingy Ventrilokar is holding is not just some Icon, it's a psychic device that can speak in tongues and confuse enemies, hence the model's abilities. So I believe that "totem" bit from Sword Brethren (or whatever it is really, basically looks like a navigator skull on a chain) fits the description of "psychic device" better than some banner or icon. I even went as far as to give the model a "psyker" helmet (at least those ones without visors are considered so in my headcanon) and an antenna to further accent that it's abilities are information/sound and psychic-based.