0 the use of a negative statement in order to emphasize a positive meaning, for example "a not inconsiderable amount of money (= a considerable amount of money)"
Overall, then, the poet has lavished considerable labour on this passage, adorning the gift-giving ceremony with both litotes and direct commentary.
The pattern for early litotes was to start with two words, mainly a positive and a negative connected by a particle.
For the use of double negations or similar as understatements (not unappealing, not bad, etc.) see litotes.
Litotes is a form of understatement, always deliberate and with the intention of emphasis.
Meiosis is the opposite of auxesis, and also sometimes used as a synonym for litotes.
Litotes, such as not bad, not much and you're not wrong, are also used, as are diminutives, which are commonly used and are often used to indicate familiarity.
Rhetorically, this becomes the device of litotes; it can be difficult to distinguish litotes from pleonastic double negation, a feature which may be used for ironic effect.