Vandal Savage's moment was from one scene... Played off as a joke, they redeem him for no reason other than a one scene joke. Which is stupid, like really stupid, imagine a villain killing women and children for shits and giggles who gets to jail and a few episodes later shown to have turned a new leaf for a 5 second joke scene.
One episode, one scene, and that's where he shows up and gets redeemed. One of the most annoying, and bizarre redemptions I've ever seen in my life which is so stupid to me. Especially considering how depraved and sadistic he is throughout the Arrowverse.