Bird Bane:
This unique longsword was created by someone with a particular desire for vengeance against Perytons. This longsword functions like a +1 Longsword (+1 to both Attack and Damage rolls). On striking a bird (or bird-adjacent creature such as a Griffon, Harpy, Hippogriff, Pegasus, or Peryton), this sword does an extra 3d6 Slashing damage. Despite being ancestors of modern birds, dinosaurs are unaffected by this additional effect.
This item does not require attunement.