How do you get Huang Gais level 11 weapon in Dynasty Warriors 4 Extreme Legends?

Reach the Wei Ship without being discovered by any Wu troops in under 3 minutes 30 seconds on Expert mode. After game start, immediately run toward the gate at the center, staying close to the left wall. When you reach the small alcove right below the gate, a message will appear

saying that the Guard Troop has heard some noises. Immediately run to the right wall.

When the Guard Troop leaves the gate to investigate the noise, run pass the gate, still keeping close to the right wall. Run directly across to the left edge along the water and continue upwards, avoiding Ling Tong. It is acceptable to be seen by the Entry Point soldiers, their discovery of you doesn't count. Move past Ling Tong when he's far away and continue upwards still keeping close to the left edge. At the turn of the land, go into arrow aiming view and watch the Guard Troop in front of that last gate, they will move forward just as Lu Meng is returning and coming close to you. After they've run a distance, head for that last gate. It is acceptable if you are seen right after passing the gate. Run past Gan Ning and sprint onto the Wei Ship. If Gan Ning discovers you at the last second, it is still good. You should get the weapon learned message at stage end, with a clear time of around 2:30 ~ 2:40. I tested, 3:30 is the limit for unlocking the weapon. 3:31 is no good. I strongly suggest trying the stage out in an easier difficulty first to get a feel of the layout of the stage before attempting to unlock the weapon.