Han Sen moved like a shadow, and Barr's slashing bone knife was unable to strike him. Han Sen couldn't counter Barr's strength directly, so he had to remain fleet of foot. Even blocking one of those blows with his Ghost Teeth Knife would damage him a great deal.
"Barr is getting stronger!" Qing Li had finally seen the problem that Han Sen was having. Barr's increase in strength was becoming obvious to all of the onlookers. And Han Sen's power remained what it was, not increasing at all.
After the power increase, Han Sen was suppressed. All he could do was keep dodging. He couldn't fight Barr anymore.
Qing Li became very worried that there might not be a ceiling to Barr's increase of strength. Even if Han Sen used all of his power, if he couldn't avoid Barr's strikes, he could be killed in one shot.