This one's easy! My favorite sword is Thorin's Orcrist, the Goblin Cleaver. Here's a lovely picture of Thorin showing it off for us. I feel like it fits his personality perfectly as well. It can't be described; anyone else know what I mean?
Gorgeous, isn't it? Yes, I know. I think I'm going to get the letter opener at some point because it's pure awesomeness.
Gandalf's (formerly King Turgon's) sword Glamdring is a close second, though, as well as Anduril. They both are classically shaped, yet have unique handles and beautiful details worth swooning over. And yes, there are letter openers of those too. :)
Ah, the loveliness. I shall swoon! I just have a thing for swords...