... dejar quisiera
mi verso, como deja el capitán su espada,
famosa por la mano viril que la blandiera,
no por el docto oficio del forjador preciada.
We know that the poet is explicitly saying that he wants to leave his verse behind, famous like the sword of the virile captain, for the captain himself, not prized for the learned crafstmanship of the forger.
But these lines, in which this message is expressed, are themselves an example of the "docto oficio." Look at how the poet makes the lines fit into the metrical pattern by altering the word order. In normal syntax, he would have said "quisiera dejar mi verso como el capitán deja su espada, famosa por la mano viril que lo había blandido, no preciada por el docto oficio del forjador." The tone and vocabulary is very culto, not popular at all. Most readers will see through the language to the meaning, instead of seeing that language itself. In so doing they kind of miss the point. Machado is saying, look, I can do this virtuosic verse thing too, even though I'd really like to be admired for other things. I'm not an aesthete, but that's by choice. He can shift tones and registers at will, like "el lecho donde yago" instead of "la cama en que duermo." Performances of humility are always rhetorically interesting, because they have to have some aspect of the "humble brag."
The phrase "docto oficio" is itself a rhetorical figure called "epithet," in which the adjective comes before the noun instead of after to connote an inherent quality of the noun.
Metrically, the lines divide up into two groups of seven syllables:
mi verso, como deja / el capitán su espada,
famosa por la mano / viril que la blandiera,
no por el docto oficio / del forjador preciada.
There is another figure of diction, I'm not sure if it has a name, but notice how the two parallel clauses have opposite word orders? He begins with "famosa" but then makes you wait to the end to get to the word "preciada."