There are many powerful trinkets and baubles hidden in every nook and cranny of Middle-earth. In fact, the One Ring of Power is just, well, one ring in a sea of magical items that make the wielders near omnipotent. It's also not just rings either; other, uh, "preciousss"... items can also be imbued with power to a certain degree.
Swords, for that matter, are no different. Depending on who wields them or who they are meant for, they can have a personality and backstory of their own. As such, they also give the wielder some semblance of power. One could argue that the magical swords in Lord of the Rings are even better than the rings. After all, they won't betray you. Here are some of the strongest.
Hadhafang is not exactly in the books, meaning it's not canon. It was merely added by the film-makers for the film adaptation of Lord of the Rings, but it's in no way lore-breaking. Based on its designated backstory, Hadhafang's original owner was Idril, an elven princess who wed a mortal man and had a child with him, named Eärendil (Elrond's father).
Hence, it was first seen (in the films) in the hands of Elrond during the Last Alliance of Men and Elves on the slopes of Mount Doom. Later on, however, Elrond gave it to Arwen, who poetically also fell in love with a human like the Hadhafang's original owner.
9 THRANDUIL'S SWORD
Thranduil's unnamed sword is similar to Hadhafang. It's also non-canon and was only added by the film-makers for The Hobbit trilogy. Thranduil's sword also shares a similar design to Hadhafang and was presumably light enough to be wielded with one hand. It's a shame that it wasn't named, since Thranduil, the Elven king of the Woodland Realm, was quite efficient with it.
In The Hobbit: The Battle of the Five Armies, Thranduil can even be seen wielding two of these blades in each hand. Like his son Legolas, Thranduil has proven that he's just too godly for a film adaptation, even with two nameless swords. His sword still gets more merit than Hadhafang, though, since we actually see it unsparingly used in combat.
Unlike the previous two, Herugrim is canon and was conceived by Tolkien himself. You might have seen it already since it's unique design is quite hard to miss in The Two Towers; its current wielder during that time is Théoden. However, it's a lot older than Théoden, having existed for 500 years being passed on to whoever is crowned the King of Rohan.
Its importance is not just limited to being a royal heirloom, of course. It proved instrumental in Gandalf healing a weakened Théoden back to full strength. If you can recall, Théoden was progressively being poisoned by Grima Wormtongue (Saruman's servant). It was because of Herugrim that he remembered his own strength better after breaking free of Wormtongue and Saruman's grasp.
Gurthang is canon but never really made it into the film adaptations. It was only mentioned in The Silmarillion but was a powerful sword nonetheless. It belonged to Túrin Turambar, a human of Middle-earth who became a tragic hero after discovering he was more of a Jaime Lannister than an Eddard Stark.
Anyway, Túrin actually used Gurthang in order to slay the dragon Glaurung. It's no mere tool for killing too. It appeared to have a mind of its own. It even seemingly spoke to Túrin when he was about to kill himself over grief since his wife killed herself (remember that Jaime Lannister part?). The devastated hero actually asked Gurthang to end him swiftly-- to which the sword replied "Yea." No kidding, it's canon (image via: Silentwitness97).
The Morgul-blade is not exactly a sword; it's more of a long dagger. Regardless, it deserves a spot in this list for causing agony to the Ringbearer, Frodo Baggins. In the films, it first appeared in the hands of the Witch-King of Angmar, the leader of the Ringwraiths, who used it to stab an invisible Frodo.
The Witch-King could have used his regular sword but he felt extra evil; the blade is reserved for Mordor's greatest enemies to be used as a punishment. That's because the Morgul-blade is innately magical and poisonous. A mere scratch on a living creature is usually enough to kill them. Its poison can reach the heart of the victim. The catch is, it turns to dust once it has tasted mortal flesh, meaning it's disposable.
The blade of the King and the weapon of choice among the heirs of the Dúnedain. In the films, it was wielded by King Elendil during The Last Alliance of Men and Elves in the battle against Sauron. Too bad that didn't end well and Narsil was shattered into pieces after Sauron defeated Elendil.
Isildur, Elendil's son and the next heir, inherited what's left of the blade. Still, even in its sorry state, it was able to slay Sauron and part his ring from him. Unfortunately, it was never repaired again and remained shards even after being passed from heir to heir. Narsil was, however, still a famed weapon for being crucial in Sauron's defeat-- the Dark Lord now fears the sight of Narsil on the battlefield.
Sting is one of the most popular swords in the Lord of The Rings and even The Hobbit trilogy. It was originally a short sword forged by the Elves, but made for a perfect weapon for Hobbits. As such, it fell to the hands of Bilbo Baggins; it has since been his signature weapon and tool until he found the One Ring.
While Sting may not be a weapon fit for a King, it arguably keeps its wielder safer than any other sword. As we know, Sting glows bright blue whenever orcs and/or goblins come near the sword. For a Hobbit, it's an indispensable tool to help them avoid bigger and faster enemies. Both Bilbo and its eventual inheritor, Frodo, have used Sting to its full potential.
Orcrist has two other names: Goblin-cleaver and Biter, the latter of which was given by goblins. They actually feared the sword so much as to give it their own infamous legend. Hordes of goblins and orcs lost their heads due to Orcrist. It was forged by the elves for that purpose and was wielded prominently by Thorin II Oakenshield, who ironically, is a dwarf.
Thorin lost it after being captured by the Elves of Mirkwood and it was later wielded by Legolas when he fought against the orc Bolg in the films. The Orcrist has also been regarded as the bigger brother of Sting. Like the short sword, it also glows whenever its intended prey is nearby, meaning orcs and goblins.
Wizards (The Istari) were generally more powerful than kings in Middle-earth. Gandalf the Grey (and later, the White) was no exception. So, apart from his staff, he wielded a legendary sword more feared than Orcrist, which is Glamdring. Of course, since it's a wizard's weapon of choice, Glamdring is no ordinary blade. The Elven smith who forged it also placed rune inscriptions on the hilt and guard of the sword.
As a result, Glamdring is one of the few swords (or possibly the only one) in Middle-earth that can pierce the Balrog's skin. Gandalf can even use it to cast spells in a similar function to his staff; the wizard called upon lightning and stored it within the blade. With Glamdring, Gandalf was able to defeat the Balrog and went on to "level up" as Gandalf the White.
Andúril was the most special sword in Lord of the Rings because it was forged (or reforged) for Aragon II Elessar. It was initially the shards of Narsil which the Elves of Rivendell (Elrond in the film) reforged into a new blade that Aragorn called Andúril. This time, however, the elves made sure to place an enchantment on the sword's sheath to make it immune to breaking and stains.
The sword, while not as innately powerful as Glamdring, was shown to be immensely influential. With Andúril, Aragorn was able to summon and command a ghost army, the deadliest ever in Middle-earth. Additionally, Sauron, upon seeing the reforged blade in all its glory, was shaken.