>> I'll say. And whatever his power is, working with it is gonna be tricky as it doesn't sound like something that's easy to practice with.<<

His source is angelic, which means he could practice accessing it simply by praying, meditating, or otherwise reaching out for the numinous. Trouble is, Cas really wants to keep his feet on the ground. All. The. Time. :/ If he could establish fluent access to his source, it would be a lot easier to apply it as needed. He's not going to like that -- but he's also not going to like undermining his ability to respond at need.

>> If he was literally holding body & soul together, maybe Aidan can give him some tips. <<

Sure. dialecticdreamer is working on that. But it's going to take a fence stretcher to pry our boy's head out of the sand.