This was all from a single attack. And he even avoided most of the damage of the attack. But the fact that he was touched by the attack, even if lightly, is enough to put him in a precarious situation.
The black-robed swordsman is also a killing cultivator, but he didn't know that Loki had used the Branch Metacs of the Killing Pathway to attack him, which was why he didn't understand how being lightly grazed had turned into serious mental and physical pain and weakness.
He didn't know that he had actually been cut once. The six cuts on his body made him believe that he had been cut six times by the explosion since Loki was clearly a forge cultivator, not a killer like him.
But despite all of this ignorance about the kind of attack that struck him and the capabilities of his enemy, he knew without a doubt that he couldn't withstand the power of his enemy and that his life was in danger.
