Question: when does castiel get his grace back season 9

title: Supernatural (season 9)
text: Crowley is addicted to human blood , but after the demon he uses to get it betrays him to Abaddon , he calls in Sam and Dean . Crowley , Sam , and Dean team up to locate the First Blade which has passed among various owners since its discovery by an unmanned submarine in the Mariana Trench . Finally , they track the Blade to a rogue Man of Letters named Cuthbert Sinclair ( Kavan Smith ) . Locating his lair , Sam and Dean learn that Magnus is a collector of creatures and rare objects such as the Blade and as he needs Dean to use the Blade , he imprisons him and sends Sam away . Sam and Crowley manage to get back in , but Sam is captured . Crowley frees Dean who kills Magnus with the First Blade , after which Sam realizes the Blade is having a strange effect on Dean . Crowley then takes the Blade as he does n't trust Sam and Dean not to kill him and will only give it back to them once they have tracked down Abaddon .