The sneak attack ability in WWM is called Touch of Death and you need to do a quest (Echoes of Old Battles) in the beginning zone to learn it.
1. Talk with Lie Bujin in the main gate of the Battlecrest Slope in Qinghe to start the Echoes of Old Battle quest.
2. Clear the enemies inside the gate.
3. Defeat the boss called Zhang Bao.
4. Find and light two Braziers. One is right where you defeated Zhang Bao and the second one is on top of the second gate.
5. Lighting both braziers will reveal a hidden platform in middle of the boss fight area. Go on top of it and do the jump and slam on it (Space and then Q in PC) to open the underground area.
6. Go down and then push the gate open.
7. Investigate the dead man in front of you and remember his pose for later.
8. Continue to your left and use the pose for the statue.
9. Look around and push this three symbols:
- 移
- 漂
- 百
While facing the statue after the pose, two is in your left and one is in your right.
10. Now open the gate in front of the statue and continue until you get to a place with a waterfall.
11. Unclog the waterwheel and open the gate. (It's behind the waterfall)
12. Loot the golden chest to get the Touch of Death.
- Don't forget to open small chests on your way.
