The original Holy Avenger is one of the 2 major campaign artefacts (the Sword and the Stone)
On Bavarik's Death the Holy Avenger is broken into 3 parts:
Hilt - Fastlaw
Blade - Agan
Tip - Rakos
Fastlaw is wielded by Bavarik's line but on Silmar's death it is also broken into 3:
Fastlaw Hilt - Merc
Fastlaw Blade - Astorin to Senforn to ...?
The scabbard of the holy avenger is powerful and important in its own right but it is not clear if the scabbard of Fastlaw is a different artefact or the same one.
Bavarik retrieved the Sword from Hades I think? There is also a matching scabbard to contain the power of the Sword but it is not clear if Bavarik ever possessed it.
Odin and Zeus have agreed that it should be returned to Zeus' dominion - not clear precisely where though. Interestingly, this is different from the perception that the Stone should be destroyed and may reflect an inherent alignment-based bias on their part. True balance is only achieved if both are returned to Outer Planes or both are destroyed.
Bavarik's sword was a Holy Avenger of significant power and is one of the 2 major campaign artefacts. It provides a direct counter-point to the Stone and is thus one of the 2 objects around which the Ages turn.
When Bavarik was defeated by Ezolach, the Holy Avenger was destroyed, breaking into 3 parts: Hilt, Blade and Tip
These were eventually reforged into 3 separate swords: Fastlaw (Hilt), Agan (presume blade due to it being the 'middle' aligned sword) and Rakos (presume tip)
(15-25) 860-870 - Siege of Minas Aarda and Death of Ynis Wydrin - Having restored law to much of the land, and driven out Demogorgan’s evil forces, Imrahir discovers that Minas Aarda is occupied by Orcus. Having re-forged Bavarick’s sword and wearing both known parts of the Crown, Imrahir leads a large force up to the gates of the ancient Minas. Having not reckoned with the power of the Demon, assault upon assault is thrown back. The siege ends in disaster for Imrahir. Ynis Wydrin is killed during the battles and Lastar’s staff is delivered to Orcus
Silmar carried Fastlaw, the Flame Brandt, aligned to Law and/or Good but, like its predecessor, it was broken into 3 parts. Merc was the last known bearer of the Hilt (the one part of Fastlaw that was part of the true sword)
Milai is the latest to carry Agan
Guerin was the last known bearer of Rakos but it is not known what happened after he was banished from the Prime.
The scabbard was retrieved from Hades' realm by the New White Council in response to a quest placed upon Dafydd, by his god Odin.