Excalibur

Excalibur is a powerful magical sword of gilded Adamantine, forged in Avalon by an Elfin Smith; Excalibur was the principle weapon of Arthur Pendragon and it was symbolic of his power and right to rule the kingdom.

The Lady of the Lake serves as the Guardian of Excalibur, protecting the sword from the hands of evil and granting it to heroes she considers to be worthy. Similar to the Oracle of Delphi, the Lady of the Lake isn't a single person but a position that can be transferred or inherited.

Each time a Lady of the Lake entrusts Excalibur to a mortal hero it is given with the expectation and understanding that the sword must someday be returned.

Though many in Camelot view Excalibur as the ancestral property of House Pendragon and birthright of the king, Nimue Du Lac (the current lady of the Lake) disagrees with this. In the 2010's when numerous claimants to the Throne of Camelot were discovered, Nimue Du Lac organized a contest called the Excalibur Trials.

Characteristics and Abilities
First of all Excalibur, as an Adamant weapon is basically indestructible. Excalibur was forged in dragon-fire and therefore cannot be broken, damaged, or destroyed except with dragon-fire or by another weapon forged using the exact same method. Excalibur is gilded with a layer of Imperial Gold.

Excalibur is capable of cutting iron as easily as wood.

Excalibur seems to imbue it's users with superhuman strength (if they didn't posses it already); allowing mortals to fight toe to toe with demigods. Excalibur can also emit fire and light. In one battle it is described as shining as brightly as thirty torches and blinding Arthur's enemies.

Fireballs and lasers can be projected from the tip of Excalibur, waves of these elements can be released while slashing the blade.

Excalibur also changes shape depending on who is wielding it.

Known Holders
Vivian Du Lac

Uther Pendragon

Merlin

Nimue Du Lac

Arthur Pendragon

Artemis Constantine