丟開解數 He Let Loose His Moves
他兩個廝罵廝打，早驚動那裡邊的女怪。他七個一擁出來，叫道：「師兄且莫勞心，待小妹子拿他。」行者見了，越生嗔怒，雙手掄鐵棒，丟開解數，滾將進去亂打。他两个厮骂厮打，早惊动那里边的女怪。他七个一拥出来，叫道：「师兄且莫劳心，待小妹子拿他。」行者见了，越生嗔怒，双手抡铁棒，丢开解数，滚将进去乱打。
逐句解 Line by line
The two of them cursed and struck at each other, and the noise soon roused the women-monsters inside.
廝 is a reciprocal prefix — 廝罵 is cursing each other, 廝打 is fighting each other — and it survives today in 廝殺, to fight it out. This is the second time in the chapter that a noise at the front of the house has brought the back of the house running; the first was two boys washing teacups.
The seven of them came swarming out. "Elder brother, don't trouble yourself," they called. "Let your little sisters take him."
一擁 is to surge forward all at once, in a crowd — the 擁 of 擁擠, crowded. 莫勞心, don't tax your mind, is a polite formula for don't put yourself out. They are still observing the seniority in the middle of a brawl.
Pilgrim, seeing this, grew angrier still. He swung the iron cudgel in both hands, let loose his whole repertoire, and went rolling in among them, laying about him.
解數 is the term of art here: the set of moves and stances a martial artist has been taught, his whole repertoire. It survives in 渾身解數, everything one has got. The reading is xiè, not the jiě of untying — 現漢 files the compound as xièshù, and both 康熙 and 中原音韻 record two bands for the character. 掄 is to swing a heavy thing in a wide arc, and 滾將進去 is literally rolling in.
The chapter's genre change completes here. Twenty passages ago this was a story about tea; now it is a brawl in a courtyard with seven women pouring out of a back room shouting that they will handle it. The vocabulary has changed with it — 廝打, 一擁, 掄, 亂打 — all of it physical, none of it polite.
The women's line is the funny one. 師兄且莫勞心 — don't trouble yourself, elder brother — is exactly what you say when an older relative starts to get up from his chair to do something you would rather do yourself. They are offering to take over a murder as a courtesy.
And Pilgrim goes in rolling. 解數 is the giveaway that the book is now writing in its combat register: this is the vocabulary of the martial-arts storyteller, and a Ming audience would have recognised the switch instantly, the way a modern reader knows when a thriller stops describing and starts choreographing.