Does the Qur'an undercut its own claim to be Allah's verbatim speech by calling itself 'the word of a noble messenger'?

No. These verses do not say that a messenger authored the Quran. They describe the Quran as the message delivered and recited by an honored messenger, while the Quran itself identifies Allah as its ultimate speaker and source.

Why the objection sounds serious

The argument is not frivolous. The Quran says:

Indeed, it is the word of a noble messenger.

Quran 69:40

And it says:

Indeed, it is the word of a noble messenger, possessing power, established with the Owner of the Throne, obeyed there and trustworthy.

Quran 81:19-21

Read in isolation, "the word of a messenger" might sound like the messenger composed the text. If that were the meaning, it would conflict with the Quran's claim to be revelation from Allah. The critic is therefore right to ask whether the wording creates a genuine authorship problem, rather than dismissing the question as mere semantics.

What "the word of a messenger" means in context

In Arabic, a statement can be attributed to the person who delivers it without making him its author. A king's proclamation may be called the word of his envoy because the envoy conveys it. The same distinction appears in ordinary English: "the ambassador's statement" may mean the statement he delivered, not one he invented.

The surrounding context makes this interpretation clear. In the same passage, the Quran says:

And it is not the word of a poet; little do you believe. Nor the word of a soothsayer; little do you remember. It is a revelation from the Lord of the worlds.

Quran 69:41-43

The point is to deny that Muhammad (PBUH) was a poet or soothsayer and to identify the message as revelation from the Lord of the worlds. Likewise, chapter 81 contrasts the Quran with the accusations of madness and poetry, then describes the messenger as trustworthy. The messenger is characterized as a reliable bearer, not an independent source.

One Quran, two levels of attribution

The Quran repeatedly calls itself Allah's speech and revelation, while also describing its delivery through a messenger. These are not competing claims. The source is Allah; Gabriel conveys the revelation to Muhammad (PBUH), and Muhammad (PBUH) conveys it to humanity. The title "messenger" may refer to Muhammad (PBUH) in one passage and Gabriel in the other, but neither reading requires human authorship.

This is also why the Quran can say that a polytheist should be granted protection "so that he may hear the words of Allah" (Quran 9:6), even though those words are heard from the Prophet's recitation. Attribution to the reciter does not cancel attribution to the divine speaker.

What the verses do and do not establish

They establish that revelation comes through an honored, trustworthy messenger. They do not establish that the messenger invented, edited, or authored the Quran. At most, they show that English phrases such as "the word of" can conceal an important distinction between origin and transmission. In context, the Quran itself supplies that distinction: Allah is the source, and the messenger is the faithful bearer.