honkshu:

The sword was found sheathed in a wooden black lacquer scabbard. The scabbard had an almost air-tight fit with the sword body. Unsheathing the sword revealed an untarnished blade, despite the tomb being soaked in underground water for over two thousand years. A simple test conducted by the archaeologists showed that the blade could still easily cut a stack of twenty pieces of paper. (via Sword of Goujian - Wikipedia)