Throw banner on other players, attaching it to their backs, but not limiting them in any way, just the banner effect aura will move with them. Other players can press F on the player carrying banner to pick it up as an environmental weapon with 4 weapon skills + 5th is throw. Aiming at allies will attach the banner, failing to hit allies will just simply place it on the ground.
Not sure if possible or advised:
- Attaching banners to self
- Attaching multiple banners to a single player