頭疼敗陣 Pilgrim's Aching Head
行者抱頭，皺眉苦面，叫聲：「利害！利害！」八戒到跟前問道：「哥哥，你怎麼正戰到好處，卻就叫苦連天的走了？」行者抱著頭，只叫：「疼疼疼。」沙僧道：「想是你頭風發了？」行者跳道：「不是，不是。」八戒道：「哥哥，我不曾見你受傷，卻頭疼，何也？」行者哼哼的道：「了不得，了不得。我與他正然打處，他見我破了他的叉勢，他就把身子一縱，不知是件甚麼兵器，著我頭上扎了一下，就這般頭疼難禁，故此敗了陣來。」行者抱头，皱眉苦面，叫声：「利害！利害！」八戒到跟前问道：「哥哥，你怎么正战到好处，却就叫苦连天的走了？」行者抱着头，只叫：「疼疼疼。」沙僧道：「想是你头风发了？」行者跳道：「不是，不是。」八戒道：「哥哥，我不曾见你受伤，却头疼，何也？」行者哼哼的道：「了不得，了不得。我与他正然打处，他见我破了他的叉势，他就把身子一纵，不知是件甚么兵器，着我头上扎了一下，就这般头疼难禁，故此败了阵来。」
逐句解 Line by line
Pilgrim clutched his head, knitting his brows and screwing up his face, and cried out, “Fierce! Fierce!”
利害 is the older way of writing the word for "fierce, formidable" and is kept as the edition prints it — the modern spelling swaps the first character for one meaning severe.
Bajie came up beside him and asked, “Brother, how is it that just when the fight was going your way you set up a wailing to heaven and ran off?”
好處 takes 處 as chù. 叫苦連天 — crying out in pain so that the noise reaches heaven — is a fixed expression, and it is normally the sort of thing this book gives to Bajie, not to his brother.
Pilgrim, still holding his head, could only say, “It hurts, hurts, hurts.”
抱著 is the ongoing-action zhe. The three 疼 are plain repetition, not a sound-word: he is simply saying it three times.
Sha Monk said, “I suppose your head-wind has come on?”
頭風 — "head-wind" — is a recognised complaint in medical writing, a chronic disorder of the head blamed on wind getting in. Sha Monk offers it as the boring explanation, the way you would suggest a migraine.
Pilgrim started up and said, “It is not that, not that.”
跳道 is "said with a start". Both 不 stand before 是 and take bú automatically.
Bajie said, “Brother, I never saw you take a wound, and yet your head aches. How should that be?”
不曾 takes bù, 曾 being second tone. Bajie's question is the real difficulty of the scene: nobody saw a wound.
Pilgrim said with a groan, “It is past bearing, past bearing. Just as she and I were at it, and she saw that I had broken through the play of her trident, she gave her body a spring — I cannot tell what manner of weapon it was — and jabbed me once upon the head; and the ache of it is so hard to endure that I have come off beaten.”
了不得 takes 了 as liǎo and 得 as the toneless de. 難禁 takes 禁 as jīn, to endure; the jìn that means to prohibit would be wrong, and the same phrase turns up later in the Buddha's mouth. 著我頭上 uses 著 in its contact sense, zhuó, "on me". The text writes 他 of the demon throughout, the pronoun being ungendered in this period; the English follows the story and reads her.
The passage is built as a diagnosis, and it works by elimination. Sha Monk proposes 頭風, the wind-disorder of the head, which is what a physician would reach for first; Pilgrim rejects it. Bajie points out that he never saw his brother take a wound at all, which is true and is the actual problem. Only then does Pilgrim describe what happened, and the description ends in an admission: 不知是件甚麼兵器, he cannot tell what the weapon was. The rhythm is comic and the content is entirely serious, because a weapon you cannot identify is a problem force cannot solve.
What is most unlike Pilgrim here is the volume. 叫苦連天, wailing to heaven, is Bajie's register, not his; and 疼疼疼 — hurts, hurts, hurts — is nearly all he can say for several lines. The Great Sage who fought the armies of heaven is reduced to holding his head and repeating one syllable while his brothers stand around asking sensible questions.
The tactical detail he does supply is worth keeping. He had broken through the play of her trident — 破了他的叉勢 — and it was at that moment, with the visible weapon mastered, that the invisible one came out. The sting is not her defence but her reserve, produced only when the fight is lost by ordinary means. She will do precisely the same thing to Bajie.