A.T. Robertson Commentary Ephesians 6:10

"Finally, be strong in the Lord, and in the strength of his might." — Ephesians 6:10 (ASV)

Finally (του λοιπου). Genitive case, "in respect of the rest," like Ga 6:17. D G K L P have the accusative το λοιπον (as for the rest) like 2 Thessalonians 3:1; Php 3:1; 4:8.

Be strong in the Lord (ενδυναμουσθε εν κυριω). A late word in LXX and N.T. (Acts 9:22; Romans 4:20), present passive imperative of ενδυναμοω, from εν and δυναμις, to empower. See 1:10 for "in the strength of his might." Not a hendiadys.