SEASON FINALE: For tonight’s Season 1 finale, it’s Supergirl vs. a super-weapon: a glowing sword made of green kryptonite. And it’s a weapon wielded by her adoptive sister, who’s still under a villain’s mind control and turned into a deadly weapon of her own. But it’s also an episode in which the caped crusadress takes to television to try to reach the populace. We knew Supergirl could take to the air – but this is a new approach entirely.