Now Krishna presents the other side. After showing what Arjuna stands to gain by fighting (2.32), he shows what Arjuna stands to lose by not fighting. If you walk away from this righteous battle, you will forfeit both your dharma and your honor — and you will incur sin.
This is not a threat. It is a clear-eyed assessment. When a person knows their duty and deliberately turns away from it, something breaks inside — a quiet erosion of self-respect that no external comfort can repair. That inner collapse is what Krishna calls 'papam' here. The sin is not punishment from outside. It is the natural consequence of betraying your own purpose.
Krishna mentions two losses together: svadharma and kirti — duty and honor. One is internal, the other external. Abandoning the fight would damage Arjuna from both directions: his own conscience and the world's regard for him.