Board Thread:General Discussion/@comment-26580042-20160826010854/@comment-27934866-20160827023435

The Holy Grail is one of many sources/origins of Magic. The Holy Grail, and The Dark One's Dagger gives the person Magic, whereas practitioners like Cora, Zelena, Regina, and Emma learned how to use Magic.

Magic is not an intellectual endeavour, it's an emotional one. Magic comes from emotion, it's not about what the person see's, it's about what the person feels. Negative emotions empower magic, whereas positive emotions control it.

The Holy Grail doesn't give the drinker just one form of Magic because the Wand that Merlin gave to his Apprentice is forged from both Light and Dark Magic, the tethering spell used to bond Nimue (and all the other Dark One's after her) to the Dagger is a form of Dark Magic, and so is the spell Merlin used to temporarily knockout the guard in Arthur's Dungeon. If Magic (of any kind) is used to commit an act of murder is what causes the corruption of a persons soul i.e. Giving in to the Darkness. It's the same with The Dark One's Dagger it doesn’t forbid a Dark One from using Light Magic.

When Emma used Dark Magic to tether Hook to Excalibur, giving him Merlin's magic in the process, it's Hook's dark past that caused him to become a second Dark One since he'd already given into the Darkness.

The Dagger that Rumple has now is most likely the fake one he used to trick Belle, and the others. The potion he poured onto Excalibur before he handed it over turned the sword into a conduit which most likely channelled its powers to another vessel i.e. The Fake Dagger, which in turn causes it to become the new vessel of the Darkness.

The only thing that bothers me is that despite Merlin, and Rumple spent centuries of practicing Magic that even after they lost it they were unable to use it. It's confusing that two of the oldest characters in the series who know more about magic than anyone else can't continue using it like any other practitioner.