Jamieson, Fausset and Brown on Ezekiel 34:16

16. In contrast to the unfaithful shepherds (Eze 34:4). The several duties neglected by them I will faithfully discharge.

fat ... strong--that is, those rendered wanton by prosperity (De 32:15; Jr 5:28), who use their strength to oppress the weak. Compare Eze 34:20, "the fat cattle" (Is 10:16). The image is from fat cattle that wax refractory.

with judgment--that is, justice and equity, as contrasted with the "force" and "cruelty" with which the unfaithful shepherds ruled the flock (Eze 34:4).