It is odious for the Kșatriyas to make away with those who cannot defend themselves like to animals brought for sacrifice.* The purport is : Lakṣmaṇa wanted to chop off the arms of Kabandha and not to put an end to its life as it was not capable of fighting, being a headless demon. And it is not proper for the Ks atryas to destroy those who cannot fight.
निश्चेष्टानां वधो राजन् कुत्सितो जगतीपतेः। क्रतुमध्योपनीतानां पशूनामिव राघव॥