A lot of critics call Galadriel a Mary-Sue, in that she's extremely good at everything without us ever seeing how she got that way. My view is that she's not powerful enough. She's described as being the only other Elf in the same league as Feanor. That's some mighty company. She should be slinging spells and going toe-to-toe with Sauron instead of getting mindforked like a punk. Given that he does overpower her, she's made it clear she won't be his queen (why would a being as selfish as Sauron even want one?) and there's a perfectly good dagger right there...why leave her alive? In fact, a trip to the Halls of Mandos would be a great way to retcon her earlier personality. I'm also not buying a word of his little "You made me" speech. Like the right hand of Morgoth gave in to despair and decided to float around the Western Ocean for all eternity.