Leafwarden

Leafwarden is a Dragon Slayer (Longsword).
You gain a +1 bonus to attack rolls and damage rolls made with this magic weapon.
The weapon deals an extra 3d6 damage of the weapon’s type if the target is a Dragon.

Leafwarden, the sword of the elf warrior
Ethvarn. The sword was embedded in Death-at-Sunset’s flesh when the dragon was slain.