The way she's holding that staff, that expression, the way she seems to be moving... it commands power in a way just beyond either mere symbolism or even magic.
Looks like she's fighting some unseen enemy, even now, and she's using her staff physically as a weapon.
Though, why she's dressed like this I cannot say. Perhaps, somebody tried to kidnap the queen, and found out too late that he had more than the guards to worry about? Or is she just challenging the viewer?