How do you get Sima Yis level 11 weapon in Dynasty Warriors 4 Extreme Legends?

Trigger the rain manually instead of wait for it to happen automatically.

Defeat 9 of the 10 enemy generals. The rain will fall automatically approximately 5 minutes into the stage. To trigger the rain manually, achieve 26 KO Count at the beginning mine field area of the game in under 5 minites. The 10 enemy generals of this stage are Zhuge Liang, Wei Yan, Gao Xiang, Wang Ping, Yue Ying, Liao Hua, Zhang Yi, Ma Dai, Jian Yong, and Jiang Wei. Defeat any 9 of them. Wang Ping's ambush troops will appear after you go up the map right path. Yue Ying will appear after you deplete Zhuge Liang's HP to approximately less than half. If Sima Yi reaches the end of the map top right path, he will successfully escape from the battlefield and end the stage. Do not make the mistake of doing so before you get the weapon, like I accidentally did the first time I played the stage, which was also the first time I tried to unlock this weapon. This must be done in Expert