The second reason Amon wanted these bandits in his force was due to their real battle experience. Despite having fewer resources, an underworld member had better combat experience compared to students trained in a controlled environment. In the same comparison, a bandit in the wilderness had even better combat experience than an underworld member. This was because when they fought, it was always about life and death. There was no rule in the wilderness. If you didn't fight hard enough, you died. Such an extreme condition bred hardy killers.
With better average cultivation and more savage battle mettle, these bandits would aid the Demon Gang greatly when things came down to a physical confrontation, which was what the current situation was. Each of these bandits served as an ideal enforcer. Even if they were still outnumbered, they didn't lose in combat power.
