Method 1 :
Defeat Xiahou Wei.
Defeat Xiahou Hui.
Defeat Xiahou He.
In any order.
All before Zhuge Liang orders the all out attack on Wei Yan
(approximately 2:30 into stage).
Method 2 :
Defeat Xiahou Wei.
Defeat Xiahou Hui.
Defeat Xiahou He.
In any order.
After Zhuge Liang orders the all out attack on Wei Yan
(approximately 2:30 into stage).
Defeat all Shu generals and sub-general as they appear Ma Dai, Guan Xing, Wang Ping, Zhang Bao, Jiang Wei).
Encounter Zhuge Liang.
Achieve 200 KO Count.
Method 1 is a pain to pull off, I definitely do not recommend it unless you
are confident of your skills fighting with Wei Yan.
Method 2 is simple enough.
With method 2, if you did not defeat Wang Ping, just increase the KO
Count to 300 and you will still unlock the weapon. Do this on Expert Mode
Get 800 kills in Hard Mode
On hard mode get 50 kills in 4 minutes
Get 100 kills in 3 minutes on hard mode
Achieve 300 KO Count in under 4 minutes on hard.
Get 100 kills in 6 minutes and 35 seconds on hard mode
Get 300 KO Count in under five minutes and win with the difficulty on hard
Achieve 100 KO Count in under 4:30 minutes on hard.
Don't let any one pass the bridge and kill all generals on hard
Kill Cao Ren, Zhang He, Xu Zhu and Xu Huang on hard mode
On hard mode, get 400 KO Count before Xiahou Duns reinforcements comes
Before your ally troops get eliminated, defeat Guan Xing and stop the rock attack on hard
Beat Hua Xin, Hua Xiong and Lu Bu in under five minutes on hard