James Hoch explains meaning of Egyptian idiom "by the hand of."
James Hoch, Middle Egyptian Grammar (Mississauga: Benben Publications, 1997), §81
Egyptian compound prepositions are by and large bound constructions consisting of preposition + noun, e.g. ḥr-tp "on top of." . . . A number of these use parts of the human body as the second element:
ḫft-ḥr "before the face of," "in front of"
m-Ꜥ "in the hand," "in the possession of," "by the hand of," "with" (a person," "because of," "from the hand of" (i.e. a letter).