وَمِنْ شَرِّ غَاسِقٍ إِذَا وَقَبَ
And from the harm of darkness when it settles. (113:3)
وَمِنْ شَرِّ النَّفَّاثَاتِ فِي الْعُقَدِ
And from the harm of those blowing upon knots. (113:4)
The wāw coordinates prepositional expressions governed by the previously expressed seeking of refuge; it is not necessarily coordinating separate full declarative sentences. Repeating min sharri gives each kind of danger a distinct place in the supplication.
The syntactic locus of coordination and the rhetorical force of repetition are separate questions: one identifies grammatical linkage, the other explains emphasis.