Zhao Fu didn't plan to show any mercy to the governmental faction, the Ancient Clans, the Hundred Schools of Thought, or Flower Moon. They had helped a lot in that battle, and he hadn't even sought revenge for the incident with the Chaos Imperial Star.
They had come to attack Great Qin time and time again. If he didn't show them who was boss, they would continue doing this without any fear.
Because these factions were discussing Great Qin's two Writs, they hadn't expected Great Qin to suddenly attack, and they responded with panic and terror.
Great Qin's Assassins didn't hold back and stabbed their hidden blades into their targets' throats, ending their lives and completing their first blood refining.