How do you get Xu Huangs level 11 weapon in Dynasty Warriors 4 Extreme Legends?

Destroy all 4 castle attacking vehicles before they set up and start attacking the castle (approximately 2 minutes into stage). Defeat all enemy generals except Guan Yu. Achieve 200 KO Count. There will be 2 Cloud Ladders in front of the 2 West castle gates and 2 Stone Toss Vehicles in front of the South castle gate. After destroying all 4 castle attacking vehicles, Cao Ren will exit the castle and attack. Don't forget to try and keep him alive. Do this on Expert