Right component supplies the sound (jiān → cán, consonant drift) and a fitting semantic echo. Traditional
殘 used
戔 (two stacked
戈 spears, 'cut down to little'); the simplified
戋 keeps the same sense. Bones plus 'cut down few' = damage, ruin, what remains. Same phonetic in
浅 qiǎn,
钱 qián,
贱 jiàn.