Joyeuse is the magic sword imbued with magic from the Lady of the Lake to be wielded by the High Monarch
of Ga'leah. In addition to the Half-Fae's magic, it is also fitted with a ruby shard blessed by the Living Flame which gives it fiery powers and resistance to flame. Due to the enchantments in the sword, it can also not be wielded by anyone save Arthur, Gwenhwyfar, or another worthy of being the High Monarch.
Joyeuse was forged by Gwydion Argall as a sword to be magically fortified by Nimue, the Lady of the Lake, and gifted to his daughter, the High Queen of Ga'leah, Gwenhwyfar Pendragon. It was crafted especially for her hand, with a strong but light blade balanced for her size and strength level. While it weighs slightly less than an average broadsword, it is no less strong or dangerous. Also included in its creation was a ruby shard, a relic of the Living Flame that had come to be in the blacksmith's possession. This ruby has special magical properties of its own.
After it was forged, it was taken by Nimue and bathed in magic. The sword can only be wielded by one of the High Monarchs of Ga'leah, or one worthy of taking their place. In other words, the sword can only be wielded by Gwenhwyfar and Arthur Pendragon, one of their children, or the 'soulmate' of one of their children. It was also fortified with a silver streak to ward off Lycans with whom Gwenhwyfar had several significant encounters in the past, and bestowed with magical, fire-based powers.
Joyeuse can only be wielded by the Pendragons or their chosen mates. Those who do not qualify to wield the sword are rewarded with a searing, burning pain when attempting to hold or lift it. The burning will become more intense the longer or the more often an individual attempts to take possession of the sword.
The sword is like any other blade until the ruby shard in the pommel is caressed and some will is exerted on the relic. The easiest use of the magic in the sword is to heat the blade. It can heated to an unpleasant warm or to state in which the blade is glowing red with heat. In its heated state, it can cut through objects that can be affected by high heat such as metal. It can also both cut and cauterize wounds with a single blow. It has proven especially useful against the Blighted who in may cases must be burned to completely exterminate them.
Joyeuse cannot shoot flame, but it can cause things to combust due to the heat of the blade itself. If the searing hot blade is touched to something flammable such as clothing, dry tinder, or paper, depending upon how flammable it is and how long the blade is contact with it, the item in question could possibly catch fire and burn until put out.
It is believed that if enough concentration is exerted, that Joyeuse could be made to catch fire itself, but Gwenhwyfar has yet to attempt such a feat for fear of the damage she might cause in learning to control it.
Whilst wearing the sword, the wielder is immune to flame and smoke because of the Living Flame's ruby shard present in the pommel.
The weaknesses of the sword lie more in the user than in the sword itself. Because of its magical nature, Joyeuse cannot be broken nor can it be stolen and wielded by another. However, it is an extremely dangerous object even in the hands of those who were meant to wield it. Used improperly, the sword can cause devastating injury and damage with the heat and flame of the blade.
Joyeuse's fiery abilites are not as effective in the cold since the temperature of the blade when the magic is not in use is typically dictated by the ambient temperature of the air. When in cold weather, Joyeuse will not warm to the same temperatures as it would in warmer climates. It may still be warm enough to be useful but would not be at full strength or power.
It is also nearly useless to use the magic of Joyeuse in the rain. The heated nature of the blade is only good for creating steam in such circumstances, and while steam can be used to burn and cause injury, it is not controllable and is as likely to cause burns to allies as to opponents.
It is possible to use Joyeuse under water, but similar rules apply to a watery environment as to a cold one. The blade will not reach its full potential underwater, and the heated nature of the blade will heat the water around it, potentially causing burns or discomfort to friends as enemies.
Joyeuse's power is rooted in the magic that comes from the ruby in the pommel. For this reason it is powerful enough that only a very powerful Fae would be able to negate or dampen the blade's effects, but would not be powerful enough to cause harm to a god or goddess through its fiery abilities.