lament, grieve, sigh, alas, ah
嗟 centers on expressing sorrow or regret through sound: lamenting, grieving, sighing, or uttering an exclamation like "alas" or "ah."
嗟 combines 口 (mouth) with 差, which likely contributes the sound and may relate to the idea of expressing difference or disparity through lament.
A mouth 口 making a sound of difference 差: imagine someone sighing "ah" when they see how things have changed, lamenting the gap between what was and what is.
For サ, picture someone sighing "sah..." in lament: the sound "sah" cues サ, and the mouth 口 is open in grief.