There's of course also the Holy Lance in the Holy Roman Empire. Allegedly it was the very weapon that was thrust into the side of Jesus on the cross. In truth it is a Merowingian blade.

Otto the Great bore the lance in the 10th century when defeating the Magyars/Hungarians with a united force from the empire. It was considered a miracle, since the Magyars were considered invincible. The lance became one of the imperial regalia of the Emperors - that's why it is today in the treasure chamber of the Vienna Hofburg. [Holy Lance] (http://bilddatenbank.khm.at/images/800/SK_WS_XIII_19_01.JPG) They also have swords that would certainly be considered "legendary" symbols of power. The blade of the lance was later refined, a nail believed from the cross was integrated. This actually damaged the weapon though, so it was wrapped with gold to keep it together.

A funny anecdote: a second "Holy Lance" appeared during the first Crusade. The crusaders had just taken Antioch in 1098, they were weakened and expected a Sarazen Army to arrive. But they didn't lose faith after an unnamed monk claimed that he had a vision that showed him the location of the lance that drew blood from Jesus on the cross. They dug in the spot beneath a church - found the lance of course, and inspired by the miracle defeated their enemy.

Unfortunately there are no accounts on how contemporaries brought together these two traditions. The participants of the crusade from the Empire, such as the chronicler Albert of Aachen, should have known both traditions

The "magic weapons" trope in fantasy literature comes largely, perhaps even mostly, from Tolkien. Tolkien, of course, was heavily influenced by Beowulf. The swords in Beowulf are not explicitly magical, but there is a very strong sense that they are respected almost as if they were.

Consider this passage (from Gummere's translation):

Nor was that the meanest of mighty helps
which Hrothgar’s orator offered at need:
“Hrunting” they named the hilted sword,
of old-time heirlooms easily first;
iron was its edge, all etched with poison,
with battle-blood hardened, nor blenched it at fight
in hero’s hand who held it ever,
on paths of peril prepared to go
to folkstead of foes. Not first time this
it was destined to do a daring task.

Notice that the sword has a name, has a history, and is almost its own character. This type of description surely had a significant influence on Tolkien's swords like Glamdring, Orcrist, or Sting--they all have names, history, and inherent power, like the swords in Beowulf.

Now, this doesn't necessarily tell us what the Anglo-Saxons thought of real swords. But we do know that good swords were quite expensive in that era, so they were rare and handed down as heirlooms. It is quite likely that a good sword in early medieval England (and, for that matter, probably Scandinavia too) would be named and considered to have mystical power.

I can only really speak for Anglo-Norman Britain, but basically, not at all. The closest I can think of is Geoffrey of Monmouth's history, which basically invented King Arthur (or at best, codified some folk tales), but it was widely mocked as being a work of fantasy within a few decades of its writing. I don't know of a single chronicle talking about its present king, or even a king in the last few generations, who had a magic sword, though that doesn't mean it didn't exist. Obviously, we can't really tell what people who didn't write chronicles thought, because they didn't write chronicles, but there's certainly no positive evidence that I'm aware of suggesting that magic swords existed in any meaningful sense. Hope that helps, and sorry!

Swords and their scabbards are given a great deal of significance in Anglo-Saxon England as expensive pieces of bling, and therefore symbols of power and heirlooms.

For an example, check out this 8th Century beauty from the British Museum.

They had maker's marks inscribed on them which, given the time frame their creation represents, suggests a whole family line of smiths (many in continental Europe, with the blades either imported or brought over in the migration) patronised by the Anglo-Saxon elite, and these swords are mentioned prominently in the wills of Æthelstan Ætheling and Ælfgar, Earl of Mercia in the 11th Century and Beorhtric of Wessex in the 9th Century.

Some swords also bore the Hand of God (dextera Dei, commonly seen on coins), a device in Anglo-Saxon art that is believed to have had a protective quality, so we could perhaps squint a bit and look at this as a Warhammer-style Magic Item. Earlier blades were inscribed with the rune of Tiw (Týr in Old Norse), the war god.

It's easy to see how swords took on a mythical significance. The problem with this period is that contemporary chroniclers are rare, so instead we have wills, remains and epic verse, so we're forced to rely on a certain amount of conjecture as to how much heroic tales reflected reality.

The Anglo-Saxon dictionary seems very well developed with regards to varieties of sword, with language donating their decoration, condition or embellishment. Anglo-Saxon/Old English is a fantastic tongue for mysticism, admittedly some of this is presentism (perhaps care of JRR Tolkien), but it's an incredibly expressive one too.

"Mael", for instance, refers to particular ornamental qualities of a blade - examples in Beowulf include "hringmael" (curving patterns) and "wundenmael" (twisted patterns) which are used to describe Hrunting, a sword that had never "failed any man who grasped it in his hands."

Hrunting, incidentally, has many of the characteristics we now associate with Magic Items (as I'm going to insist on calling them). However, Hrunting was a fictional sword in a fable, so there's a cap on how much we can take away from that!

However, two phrases used to describe both Hrunting and real historical blades are "atertanum fah", which means (roughly) "twigs of venom", and "fyrwylmum fah", which means "surges of fire", in reference to the shapes in a pattern-welded blade. This particularly evocative reference - and its variations - to the sword's visual allure and its killing power crosses over from inventory to mythology.

Throughout the Anglo-Saxon (and Anglo-Dane) world, there's a sense that swords are important. So important to be worthy of detailed description, but also so meaningful that their language crosses over into the legendary.

Sources: The Sword in Anglo-Saxon England: Its Archaeology and Literature, Ancient Weapons in Britain and Text and Picture in Anglo-Saxon England

The sword Durendal comes from the literary Matter of France and was said to have been owned by Roland, one of Charlemagne's closest knights. It was said to made by the famous Wayland the Smith and has relics embedded in it. Although it is from a piece of literature there is still plenty of myth and legend that has followed it since then. In Rocamadour in France there is a sword embedded in a crack up the side of a cliff and though it is officially called a replica the local legends and folklore from medieval monks still call it as the actual Durendal.

On the topic of Charlemagne, Joyeuse is a sword attributed to be Charlemagne's personal weapon and has been used in the coronation of French kings from 1270 to 1824 and is said to be made by the same Wayland the Smith as well as having the Holy Lance embedded in its pommel (Yes, another Holy Lance, there quite a few of them back then). Of course the sword itself has been repaired and redecorated so many times since its first use as a coronation sword that it is unsure how much of it could be considered the original sword if it did existed.

In medieval Ireland? No, not really. Battle itself held supernatural significance and battle-magic appears to have been used, especially earlier in the period, but weapons seem to have been merely an extension of a warrior's prowess in combat which could be augmented by supernatural means. Basically, individual weapons were less important than a warrior's skill in wielding them, and that skill could be influenced by magic or prayer (which often just resembled pagan magic but was directed at Jesus or St. Patrick). Some mythical texts like the Cath Maige Tuired talk about magical swords like the Sword of Núadu that would kill any enemy when drawn from its sheath, but it is exactly that: a myth.

Swords seem to have been mainly status symbols of the aristocracy and weapons of secondary importance in contrast to Germanic societies. They seem to have mostly been markers of aristocracy and commonly appear on tribute lists owed by various Irish kings to their over-kings. Literary and historical evidence tells us that Irish swords were richly decorated and trimmed with gold or ivory but they don't seem to have been as significant or as highly regarded in Irish warfare as spears and javelins, or more specifically, skill in wielding spears and javelins.

I don't know much about European history, but one of the "legendary" weapons in the folklore of my country (Malaysia) is a kris known as the Taming Sari. Owned by the legendary "war leader"* named Hang Tuah, it is said to make its owner invulnerable, among its other mystical powers. However, this is not owned by the sultan (king); in fact, while the weapons of royalty has a lot of reverence attached to it by the virtue of its office holders, people don't actually think it has powers.

Among the Malay peoples of South-East Asia, some weapons (mostly kris) are known as pusaka (heirlooms) and is believed to have supernatural creatures inhabiting it, thus granting its owner superpowers. Of course, in exchange, certain rituals must be regularly carried out, lest said creature turns on its master. This presents a big headache to the local Islamic clergy, since such beliefs clearly goes against accepted Islamic orthodoxy. And yes, said beliefs and rituals are still present today, although obviously most of the younger generation do not follow this (and besides, pusaka is pretty rare anyway).

* the name of Hang Tuah's position is laksamana, and this post is given to the person in charge of the country's land forces. I don't know what the English equivalent is, so I had to go with "war leader". I may or may not have been influenced by World of Warcraft.