Shadow Harness is easy to get, first go to legend of Cao Cao in any difficulty, then go kill all the officer as fast as you can. And by the way, you need to kill Zhange Fei last. After you killed Zhange Fei, wait for Guan Yu to appear. Then let him escape. Wait for awhile. Then it will say in the screen that a valuable item has been found, then press start and go to history and look at where is the item is located.