ashamed, humiliated, shameful
慙 centers on a deep, personal feeling of shame or humiliation, often tied to a sense of moral failing or disgrace.
慙 combines 斬 (historically associated with cutting or severing) with 心 (heart/mind), suggesting a heart cut by shame or a feeling of being morally severed. The exact historical development is uncertain, but the phono-semantic structure is plausible.
The top 斬 looks like a cutting tool, and the bottom 心 is the heart. Imagine your heart being cut by shame, leaving you feeling deeply humiliated.
For ザン, picture a person so ashamed they feel like a 'zan' (a made-up name for a shameful outcast) — the sound 'zan' echoes the cutting shame in their heart.