黑曜石砍刀（Obsidian Machete）是使用黑曜石升級過後的砍刀。它可以在藏寶地中的藏寶裡找到。它也可以使用 1 個砍刀、1 個龍心和 3 個黑曜石合成，不過它需要在黑曜石工作台附近或裝備思維風暴帽子時才能合成。The Obsidian Machete has 250 uses, 2.5 times as much as the regular Machete, and works 2.5 times more efficiently than the regular counterpart. Initially, the Obsidian Machete deals 29.92 per swing when used as a weapon, similar to Machete and Luxury Machete. As the Obsidian Machete is used (either as a tool or a weapon), its charge level will increase causing it to deal up to 2x damage based on the number of charges. As the charge level increases, the Obsidian Machete will also produce heat and light, which protects the players from Charlie, but can cause Overheating. After gaining 75 charges, it will start igniting any Mobs and Plants struck. The charge level decrease over time as long as the machete isn't used. Obsidian Machete will not gain any charges during Hurricane Season. Similar to Thermal Stone, the machete will start glowing as it gains charges.
Players should take caution when using an Obsidian Machete with high levels of charge, as any plants ignited by the Obsidian Machete can potentially ignite other nearby trees, resources or Structures. When using this item as a weapon, players should remember that the Mobs that are killed while on fire will drop cooked variants of the food items and Ashes for flammable resources they would otherwise drop. Some Mobs will also panic when on fire, running in random directions, potentially igniting other mobs, resources or Structures around them.