Thunderspine Sword is an all-powerful Legendary Cursed Blade found only in special loot on Raven's Cove or Isla Tormenta. This lethal and powerful blade is the most powerful cutlass in the game at this time and an extremely desired weapon by many. It has a powerful Shock Sweep. It is a bit similar in appearance to the Spinecrest Sword, in spite of the cursed spines on the blade, presumably made of bone. It appears to be made of cursed spine bone of some sort. It is the only Legendary Weapon with Critical Strike, making this an extremely desired blade throughout the Caribbean. It is wanted by many, many players, but only an extremely lucky few have found it and now pridefully wield it.
- Attack: 95
- Abilities: Shock Sweep (3), Critical Strike (3), Thrust Boost (3)
- Level Required: 30 Sword, Mastered
- Resale Value: 515G
- Cost: Can only be found in Loot in Raven's Cove and Isla Tormenta.
- Best Cutlass in the game so far.
The Thunderspine Sword is the best cutlass at the moment in Pirates Online.