You can create the Diamond Sword in your Crafting Menu (default key "Q") or at Crafting Tables (which still exist in older worlds) after unlocking the according crafting recipe by crafting (or taking) an Iron Sword. Sometimes you can get Diamond Swords as a loot from the Thing on the Corruption layer too.
To craft one Diamond Sword, you'll need
- 4x Warmworm Tooths
- 3 Arctic Miru Eye obtained as a loot or pet-harvest from Arctic Mirus that spawn on Snow in darkness on Mountains, in Taigas, Tundras and on frozen Oceans. Please note that red-orange Miru Eyes cannot be used for this crafting recipe
- 3 Diamond (bars) made in a Forge from Diamond Ore
- 2 Iron Rods made of Iron Bars in a Processor or found in Iron Treasure Chests or in Diamond Treasure Chests
- 2 Obsidian Rods made of Obsidian (bars) in a Processor or found in Iron Treasure Chests or Diamond Treasure Chests
Crafting/taking the Diamond Sword is the unlocking requirement for the crafting recipe of the Lumite Sword.
To use any sword you must first equip it with a right click from the inventory or a quickslot until you can ready it for attack with TAB (default key).
Whenever you hit a creature with a sword, the weapon will lose a bit of durability until it will fall apart completely. The durability is indicated by a bar over the icon of the sword - in your equipment slot next to your character's portrait as well as on the main screen in the weapon slot. You might want to be prepared and take a new sword with you if your current one already hasn't much durability left!