The headword phrase is (neuter) plural, but its noun, as LSJ notes s.v., is frequently in plural for singular.
As Adler notes, this entry closely resembles the scholion (A) to Homer, Iliad 21.502-3 (web address 1) attributed to Aristonicus. There the verb is me/mixe not sune/mice, while Erbse cites the Suda text as e)pikamph=, which is the correct form.
[1] "A formular phrase that does not precisely suit its context, as it must refer to bow and arrows together" (Richardson ad loc).
[2] The choinix and the kotyle were units of dry measure (roughly equivalent to a quart and a cup, respectively), and also the name for vessels of approximately that size; cf. kappa 2166, chi 591.