國丈爺爺 The Royal Father In Law Comes
那國王正要問取經原因，只聽得當駕官奏道：「國丈爺爺來矣。」那國王即扶著近侍小宦，掙下龍床，躬身迎接。慌得那長老急起身，側立於傍。回頭觀看，原來是一個老道者，自玉階前，搖搖擺擺而進。那国王正要问取经原因，只听得当驾官奏道：「国丈爷爷来矣。」那国王即扶着近侍小宦，挣下龙床，躬身迎接。慌得那长老急起身，侧立于傍。回头观看，原来是一个老道者，自玉阶前，摇摇摆摆而进。
逐句解 Line by line
The king was just about to ask the reason for the scripture-fetching when he heard the officer of the presence announce, "The Royal Father-in-Law is come!"
The interruption is the plot arriving. 當駕官 is the officer attending on the throne that day. Note that the king never gets to ask his question — the novel has him reaching for an interest in something other than his own health and being cut off before he can.
The king at once leaned on a young attendant, struggled down from the dragon couch and bowed to receive him.
著 is zhe, the running marker — leaning and staying leant. 掙 zhēng is to force one's body to do something it does not want to. A reigning king gets off his own throne, on somebody else's arm, to bow to a visitor.
The elder was so flustered that he rose hurriedly and stood aside.
慌得 puts 得 at the reduced de, hooking the fluster to what it made him do. And 傍 is páng again, to one side — the third of the chapter's three, and the only one not part of a fixed pair. Tripitaka has grasped instantly that whoever this is outranks him.
Turning his head to look, he saw that it was an old Daoist, coming in from before the jade steps with a lordly swagger.
搖搖擺擺 — swaying and rolling, two doubled words, the walk of a man who has never been told to hurry. He is entering the throne room from inside the palace, not from the gate: he lives here.
The chapter has been talking about this man for two thousand characters and here he finally is, and the novel gives him an entrance built entirely out of other people's behaviour. The announcement interrupts a king mid-sentence. The king gets off his throne. Tripitaka scrambles out of the way.
Not one of those three reactions is described as fear. They are all protocol, and that is what makes them frightening: this is simply how the court works now. A monarch too weak to complete a bow will get up off the dragon couch for this visitor, and everybody present treats it as normal.
The word for his walk is the giveaway. He swaggers in past the jade steps, where the elder has just had to stand at the bottom to make his obeisance.