All of the following are weapons or tools the protagonists in various forms of media wield.

1. Sword, from a Book, Magical properties, is Unique in the Universe, from a Novel Series - The Sword of Truth, guessed by /u/WhiteMagicalHat

2. Gun, Video game, Does not fire solid projectiles - The Portal Gun, guessed by /u/joelanbanks

3. Sword, from LotR, wielded by a member of the Fellowship - Aragorn's Andúril, guessed by /u/joelanbanks

4. Tool, Magical properties, From a Comic book (DC) - The Green Lantern Power Ring, guessed by /u/King_Of_What_Remains

5. Sword, Video game, RPG-elements, Magical properties, Wielded by the Protagonist, is Unique in the Universe - The Master Sword from The Legend of Zelda, guessed by /u/RadioactiveSpoon

6. Sword, from a Japanese manga, Capable of Transforming - A Zanpakutō, from the manga/anime Bleach. Guessed by /u/LambentEnigma

Good luck!

PS. Can I just say it's really a lot of fun seeing you guys get closer and closer and guessing the right answers. I just hope I didn't make any big mistakes that are throwing you guys off :(

Update on no. 1, I put the following in the comments, but I'll put it here as well:

The sword turns the wielder's anger into power. Essentially, the angrier you are, the more connected to the sword. In this state, it gives the user cues of incoming danger and can deflect or withstand certain forms of magic. It also makes it so that if the wielder doubts the guiltiness of the one it cuts, the sword does not cut through them. When the wielder actually gains control over the magic and anger, they turn the sword white and can cut through anything they want, using their love and forgiveness. The sword is indestructible to any means in the universe and will consume the soul of those who wield it unless you are the true wielder.

The book series is about a dude living in a part of the land where there's no magic, separated from the magic part via a magic barrier. He doesn't know that a war is being waged on the other side until a woman comes over looking for a prophesized hero (which turns out to be him of course). They then go to the main Wizard in the magic world and he gets the sword and after many trials he defeats the evil dude with the help of magic and shit.

That's book one.

After book one it turns out there's another land, way bigger and way more dangerous. Full of magic users that want to end the world as it is now. It's all about magic, war, humility versus egocentrism, and love and romance and shit too.