The Coral Sword is another family-killing Weapon with attributes identical to the Wyrmkiller. If you have any party members using the Rune Blade or Werebane, the Coral Sword serves as a slight upgrade. It is useful while sailing the seas, as it can hit the high-evasion Aquatic creatures more easily than other Weapons. You may be surprised to learn that no river-dwelling creatures are of the Aquatic type, and by the Time you run into Aquatic creatures in the Sunken Shrine, this Sword will be quite obsolete.
The Coral Sword is another family Weapon with attributes nearly identical to the Dragon Sword. It has a higher crit rate, making it a good replacement for that Weapon.