This root form (lemma) is used in 3 different forms in the NT: βραχίονι (DMS), βραχίονος (GMS), βραχίων (NMS).
It is glossed in 3 different ways: ‘his arm’, ‘the arm’, ‘arm’.
OET JOHN 12:38 Greek word=βραχίων (braⱪiōn) Morphology=NMS English gloss=‘arm’ SR GNT JOHN 12:38 word 18
OET LUKE 1:51 Greek word=βραχίονι (braⱪioni) Morphology=DMS English gloss=‘the arm’ SR GNT LUKE 1:51 word 4
OET ACTS 13:17 Greek word=βραχίονος (braⱪionos) Morphology=GMS English gloss=‘his arm’ SR GNT ACTS 13:17 word 27