He knew very well that Jiang Shu's earlier jab wasn't a case of bad aim, but a conscious decision to go easy on him.
If he didn't learn his lesson now, he might end up being killed in public.
Jiang Shu, after all, was a man who could sever a lady from the Prime Minister Residence's hand. What would a mere attendant like him amount to in his eyes?
He was half-right in his guess.
Jiang Shu had acted so harshly towards Bai Zi because she had harmed Su Luo, who was completely innocent. Even if he had severed a hand, the matter, if taken to His Majesty, would result in mere admonishment at most.
But the attendant who had come to bring the news claimed that no matter the cause, Su Qing's sword had indeed slit Bai Yi's throat.
In this matter, Su Qing had no justification.
Jiang Shu's move was only for deterrence; he could not kill this attendant in public. He himself might not care, but doing so would only escalate the situation.