Go on Lu Meng's legend on Expert Defeat Zhou Cang.
Defeat Liao Hua.
Defeat Guan Ping.
Guan Yu angered message.
Achieve 50 KO Count.
It is acceptable if ally generals defeat Zhou Cang and Liao Hua. I suggest saving after receiving the weapon learned message, because Guan Yu is retreating pretty quickly, and it is just possible that you might fail to stop him before he successfully retreats and thus lose both the battle and the weapon.
Get 800 kills in Hard Mode
On hard mode get 50 kills in 4 minutes
Get 100 kills in 3 minutes on hard mode
Get 100 kills in 6 minutes and 35 seconds on hard mode
Achieve 300 KO Count in under 4 minutes on hard.
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