Beirmoura

Beirmoura was a legendary sword of Thentia. Known also as the "Bright Sword" of Thentia, it was forged to slay wizards.

Powers
Beirmoura was a sentient weapon capable of hovering in the air. In addition to such powers, it was capable of casting detect invisibility, 10' radius and ESP as a single spell, three times per day. It also reflected magic 100% of the time, absorbed magic missiles, and was immune to fire, heat, and electricity, though it was weak against cold. The sword was telepathic, capable of reading any language or magical script.

It was also a spellcaster in its own right. Amongst the spells it knew in were fireball, lightning bolt, magic missile, haste, see invisibility, and stoneskin.

History
Per a book, "The Cult of the Bright Sword", the blade had been created as part of a series of wizard-slaying swords by a mage a long time ago, in order to slay the wizards of Netheril, and at some point a cult around it had sprung in Thentia. Per Elminster, it was uncertain whether the sword held an evil entity from the outer planes, perhaps a wizard- or perhaps there was an even darker power behind it.

Around 1367 DR, there existed a sort of cult in Thentia that venerated this sword. Around that time Beirmoura traveled throughout the dark underpassages of Thentia, tracking down anyone with a magical item that crossed its path. Per Beirmoura itself, it was wielded by an adventurer who was slain by wererats in Thentia's sewers. Those wererats were its first worshipers. The wererats were later slain by the guard; one of the guards took it and later became Watchlord, which allowed the blade to spread its influence widely.

Per his journal, Bale Khodolis of Thentia acquired this sword in and used it to slay a rival of his', Gideon Birneir. Several tendays later, the sword asserted its will over him, using him to organize a "Thentian Resistance Army" made of his fellow, inexperienced nobles for an attack against a Shadovar search party in the ruins of Candlemas. Beirmoura joined the Hero of Daggerford that year as a companion; the shared information regarding the sword Dominion, one of the Five Blades of Netheril which it intended to hunt down and bury out of reach.

Rumors
Travelers' tales supposed that the Bright Sword cult was inspired by the Ghost Swords of Turmish, which appeared to protect and aid the people of the land.