הָאִישׁ֙ הָרַ֣ךְ בְּךָ֔ וְהֶעָנֹ֖ג מְאֹ֑ד תֵּרַ֨ע עֵינ֤וֹ בְאָחִיו֙ וּבְאֵ֣שֶׁת חֵיק֔וֹ וּבְיֶ֥תֶר בָּנָ֖יו אֲשֶׁ֥ר יוֹתִֽיר׃
너희 중에 유순하고 연약한 남자라도 그 형제와 그 품의 아내와 그 남은 자녀를 질시하여
Rashi
הרך בך והענג THE MOST TENDER AMONG YOU AND THE DELICATE — רך and ענג are one and the same person; the words denote delicate living. The expressions in v. 56 ומהתענג ומרך prove regarding them that both of them (the two descriptive terms) refer to one person. The meaning of the verse is: Although he may be fastidious and his nature sickens at anything nauseous, yet the flesh of his sons and daughters will be so pleasant to him on account of his hunger, that תרע עינו HIS EYE WILL BE EVIL towards his remaining children, מתת לאחד מהם מבשר בניו THAT HE WILL NOT GIVE TO ANY OF THEM THE FLESH OF HIS CHILDREN — their brothers, אשר יאכל WHOM HE WILL EAT. — Another explanation of הרך בך is: the merciful and tender-hearted will become cruel because of the great hunger and will not give of the flesh of their children who have been killed to their remaining children.
Chizkuni
אשר יותיב, “whom he has remaining;” a reference to the enemy, or: the remnant in hiding. (Ibn Ezra)
Ibn Ezra
The antecedent of the verb he has spared is either the enemy, or some-one who spared the children by hiding them (such an act having been necessitated by the circumstances of the siege).