The Juan and Kostan brothers were also present at the fight. As experts in heavy soldier defence, they had suffered great losses beneath this combat technique. Having experienced it first hand, their words had a lot of weight when it came to discussions about it. All-Mouthy King's finishing strike on Kostan was also on a level higher than the Oscillating Fist and was more difficult to defend against… because it seemed as though the second wave of force generated ignored all defences and damaged the target internally.
The second wave of force from Oscillating Fist could be defended against. Heavy soldiers with experience could definitely block it, but not completely nullify it.
Even Kostan couldn't 'negate' the effects like All-Mouthy King. Blocking and negating were two totally different concepts.
This detail was sufficient to make everyone in the elite division tremble with fear.