兄弟不睦 To Set Us Brothers At Odds
八戒聞言大怒，舉釘鈀，當面罵道：「我把你這血皮脹的遭瘟！你怎敢變作你祖宗的模樣，騙我師兄，使我兄弟不睦？」你看他沒頭沒臉的使釘鈀亂築。八戒闻言大怒，举钉钯，当面骂道：「我把你这血皮胀的遭瘟！你怎敢变作你祖宗的模样，骗我师兄，使我兄弟不睦？」你看他没头没脸的使钉钯乱筑。
逐句解 Line by line
Eight Rules heard it and was furious. He raised his rake and cursed him to his face: "You blood-swollen, plague-ridden thing!
This is a string of abuse rather than a description, and the book gives it to Eight Rules unedited. 血 is left at the literary xuè. The colloquial xiě is registered elsewhere in this edition only as a named exception inside 血淋淋, which implies xuè is the ordinary value; the street flavour of the insult argues the other way, and the site is noted rather than settled. 當面 takes dāng.
"How dare you take the shape of your own grandsire to cheat my elder brother and set us brothers at odds?"
Here is the joke inside the insult. 祖宗, "your ancestors", is a standard vernacular boast — to call yourself the other man's forefather — so Eight Rules objects to being impersonated by claiming the impersonator wore the face of his own senior. (不 rises to bú before the falling tone of 睦.) 模樣 again takes mú.
See him now, laying about with the rake anyhow, at head and face alike.
沒頭沒臉 is to strike without aim or discrimination, both 沒 taking méi. 你看他 is the storyteller turning to his audience mid-action, a habit the written novel keeps from its origins in oral performance and uses at the moment a fight turns.
Eight Rules' anger arrives late and lands in exactly the right place. He has just been blamed for a loss caused by somebody wearing his face, and what he objects to is precisely that: not the theft of the fan but 使我兄弟不睦, the setting of brothers against each other.
The abuse is worth noticing for how it sounds. 血皮脹的遭瘟 and 你祖宗 are street language, and the novel prints them unedited. He is the only member of the party who curses like this, and the coarseness is part of how the book keeps him distinct from the Great Sage, whose insults are wittier and colder.
沒頭沒臉的使釘鈀亂築 ends the passage on undisciplined violence, and the phrase is not admiring. Eight Rules fights without aim. It is nonetheless enough, as the next passage immediately shows.