I - in contrast to the false prophets (Mic 3:5, Mic 3:7).
full of power - that which “the Spirit of Jehovah” imparts for the discharge of the prophetical function (Luk 1:17; Luk 24:49; Act 1:8).
judgment - a sense of justice [Maurer]; as opposed to the false prophets’ speaking to please men, not from a regard to truth. Or, “judgment” to discern between graver and lighter offenses, and to denounce punishments accordingly [Grotius].
might - moral intrepidity in speaking the truth at all costs (2Ti 1:7).
to declare unto Jacob his ... sin - (Isa 58:1). Not to flatter the sinner as the false prophets do with promises of peace.