未曾托著 The Pagoda Not In His Hand
所以稱為托塔李天王者，此也。今日因閑在家，未曾托著那塔，恐哪吒有報仇之意，故嚇個大驚失色。所以称为托塔李天王者，此也。今日因闲在家，未曾托着那塔，恐哪咤有报仇之意，故吓个大惊失色。
逐句解 Line by line
And that is why he is called Li the Pagoda-Bearing Heavenly King.
稱為 keeps 為 at wéi, to be called. The whole digression has been an answer to a question nobody asked aloud — why does this god carry a pagoda about — and here is the answer landing.
Today, being at leisure at home, he had not got that pagoda in his hand, and fearing Nezha might mean to take his revenge, he was frightened into going white with shock.
著 is zháo here, the reading that marks a thing achieved rather than merely attempted: he had not got hold of the pagoda. It is not the zhe of an action going on, which is what the same character will be doing again before this scene ends. And here the whole hundred and fifty characters of digression pay off in one clause — the pagoda was on its stand, so for the length of one sword-block the Heavenly King was an ordinary father alone in a room with the son who wants him dead.
This is the reason for the white face, and the novel has taken the long way round to it on purpose. Without the story, the Heavenly King is startled; with it, he is terrified.
It is also a small masterpiece of plotting. A god is safe only while holding a particular object, and he has left it on a shelf because he was at home and off duty.