Tang Yin nodded toward her.
"The Heir of Death is not just any living being. I fought him recently and lost miserably. Although I was able to wound him and make him expend a lot of his power, his death skills are meaningless."
"I was able to confirm that what the legend says is true. If he gets a little stronger, I'm sure he could destroy the entire upper plane all on his own."
What he felt fighting against the Heir of Death was that he was powerful and could 'cut' his cultivation. One of the reasons he lost to the Heir of Death was because the Heir of Death managed to deliver blows that took off his arms.
When a cultivator loses a limb, his power decreases drastically. In this case, it is more exaggerated, for that guy's spiritual energy is death energy. That means he didn't 'cut' Tang Yin's arm; instead, he killed Tang Yin's arm, converting the spiritual energy that resided there into dead energy.