Board Thread:Spoilers!/@comment-11468987-20151019022445/@comment-6175354-20151020201812

Did you forget that the Dark One lies and that the Dark One tricks?

The Darkness wants Emma to give into every selfish and dark desire.... to snuff out the Light. You cannot just mold someone into a hero, especially a blank slate. The title of hero is something that must be earned, through being selfless. The  true hero would use Excalibur, to snuff out the darkness. Which is that last thing the Darkness would want.