How do you get Zhang Liaos level 11 weapon in Dynasty Warriors 4 Extreme Legends?

Keep all 4 map top castle ally Guard Troop Captains alive until Zhou Tai appears (approximately 5:30 to 6 minutes into stage).

Achieve 300 KO Count on Expert mode. Defeating enemy generals is not a part of the requirement, but it is nevertheless recommended, for doing so will raise ally morale and prolong the survival of the ally base. Li Dian does not need to be kept alive. Bring your strongest bodyguard team with you, and leave them with the Guard Troop Captains when you need to venture far away from the castle gate. Equip the Morale Drum if you have it, it does help.