They called it an aura. They made aura MTX global. That hopefully means you can change it to a regular aura via mtx.
Aura MTX replace the aura effect of the skill - banners by default have no aura effect, but my understanding is you can add one with microtransactions (effectively replacing their blank effect), in which case it will show around you while carrying the banner, or around the banner itself once placed.
I'm not aware of any specific microtransactions in 3.5.0 to replace the banner object with an alternate one, but it seems likely those might happen eventually.