What can make these scum who had seen practically some of the worst things humans have to offer, to tremble in fear you might wonder.
If Eric was here, he would have recognized it right away, because it was something that left a big impress on him, and was now taken to a whole new level as Aster is way stronger now than back then.
Normally when Aster uses the manifestation of the paragon body, the armored arms, legs and truck which is what he has unlocked so far, are strong, vibrant and full of life, that is because they derive from a body constitution, which ultimately reflects the monstrous vitality Aster has.
You could say Aster and the armor are two sides of a coin, back then when Aster first met the twins more specifically when he fought Alessia, his wish for a stronger power and a life and death situation allowed him to learn the ability "compression", something that multiplied his strength in exchange for reducing his reach.