I’m not sure what you mean by “good arm.” In Jain tradition, the names of Tirthankaras and sages are chosen for their meanings and virtues, not for any reference to a body part or “arm.” The names are usually Sanskrit-derived and symbolize qualities such as fearlessness, compassion, truth, renunciation, and spiritual victory. For example, some well-known Tirthankaras are Rishabhanatha, Ajitanatha, Sambhavnatha, and Mahavira. Each tradition (Digambar and Shwetambar) has its own accepted forms and pronunciations, but the core idea remains: names express virtuous qualities.

If you can share a bit more about what you mean by “good arm” (e.g., a specific phrase, a verse, or a tradition you’ve heard), I can give a more precise Jain-focused explanation.