Singing Dawnblade

The Singing Dawnblade is a sword that Scanlan Shorthalt used before acquiring the legendary Mythcarver. Scanlan asked Kerrek to modify the scabbard to create a tiny storage slot, into which he inserted a dab of Scanlan's Poo of Scrying before giving the sword to his daughter, Kaylie.

Properties
Because Scanlan so rarely makes weapon attacks, the Singing Dawnblade saw very little use even before it was replaced by Mythcarver. However, we can glean the following from Scanlan's two attacks with the sword in :

The sword attack is 1d20 + STR + Proficiency. The damage die is at least a d8. When Scanlan attacked and hit, he was able to make a second attack with disadvantage.

College of Lore bards can only use two types of swords with a damage die larger than a d6, longswords (slashing) and rapiers (piercing), and Scanlan's attacks are described in slashing motions.

Notable uses
Scanlan used the Singing Dawnblade to decapitate King Murghol.

Trivia
When Scanlan Scried on Kaylie for the first time, Matthew Mercer said that Scanlan had given Kaylie the Aberration Bane longsword. That seems to have been a mistake, rather than a different name for the same weapon: Scanlan gave Kaylie the Singing Dawnblade in and he used the Aberration Bane longsword in.