Board Thread:General Discussion/@comment-25926288-20160323005213/@comment-24674051-20160323213647

I tend to agree with CDA.

Rumple - Being the Dark One, his magic is sourced from the darkness within him, and is generally unaffected by his surrounding, so long as magic is available. Recall that when he brought magic back to storybrooke after the first curse broke, HE didn't have any problems with magic.

Emma - Savior Magic/Light Magic. She is the source of her own magic. As we have seen, she is able to draw on her magic even in the LWM (recall the carnival with Ingrid, and also the airport scene with Rumple). Her time as the DO gave her some additional insight into her capabailities (Like Heart ripping and teleportation), but did not fundamentally change her natural power. Presence of Magic makes her job easier.

Cora - Here, Cora had ample time to learn the rules in the UW before we see her, so she's fine. Also, she is dead, so perhaps that helped with her magic in the UW.

Regina - She's not dead, so she's really a visitor to the UW, and not a resident, which could make her use of magic more difficult. Also, it could be a case that her magic did not start working until her name was on a headstone, meaning that her magic, and perhaps anyone else that uses magic, must be "resident" in the UW. In either case, I don't think it was a confidence thing, though it not working could momentarily shake her confidence.