Ephraim. The mention of Ephraim is not "perplexing". See explanation in next verse, and in the events of Jdg_12:1-6; Jdg_12:17, Jdg_12:18 : viz. the introduction of idolatry. It is sin which is spoken of. See Psa_78:57, "deceitful bow". Compare Hos_7:16; Hos_10:6-8.
carrying bows: i.e. though equipped as bowmen, yet were faithless. This is transferred to the moral application.