The word extreamly used in this passage is an adjective describing the noun amiss. The word extreamly helps to give importante to the word amiss, to understand just how wrong being beaten made the character feel. The way the paragraph is written is very calm, but with the help of this adjectives we can understand that the character was not really relaxed, he was aggravated by the actions of their brother. It also helps explain the rest of the paragraph; since the narrator felt extremely hurt about being beaten, he wished for an opportunity to escape the situation.