How do you get Jiang Weis level 11 weapon in Dynasty Warriors 4 Extreme Legends?

Defeat all 4 playable enemy generals plus 1 of the 2 generic enemy generals.

Keep eliminating Liu Shan's destination enemy entry points to stop him from retreating for 8~9 minutes, all the while keeping Liu Shan's HP at approximately more than half. In simpler terms, just defeat Cao Ren, Zhang He, Xu Chu, Xu Huang, plus either Deng Ai or Zhong Hui. And keep eliminating for 8~9 minutes the constantly reviving enemy entry points that Liu Shan is headed towards to surrender. Also, if Liu Shan's HP reaches approximately less than half, and says " (Isn't there anyone who can rescue me?)", the weapon is lost. A chance trick is to bring your strongest bodyguard team into the battle, and leave them right where one of the entry point captains will reappear, if you're lucky they can buy you some extra time by lowering the entry point

captain's HP a little before you reach him, or if you're very lucky, defeat that entry point captain for you. But since this is Expert Difficulty after all, don't count on that.