a.the shepherd of worthlessness = the worthless shepherd
b.concretely worthless gods, idols
Strong's H434אֱלוּל: good for nothing KJV:thing of nought.
Strong's H457אֱלִיל: good for nothing, by analogy vain or vanity; specifically an idol KJV:idol, no value, thing of nought.
Meanings: Brown-Driver-Briggs (1906) and Strong's Hebrew Dictionary (1890), public domain, via the Open Scriptures Hebrew Bible Project (CC BY 4.0). TWOT numbers for reference only.
Root family 99: אללʾll — to be weak, insufficient, to fail