curse
詛 centers on a spoken wish for harm or misfortune: a curse. The meaning is narrow and direct, with no major distinct senses.
詛 combines 言 (speech) with 且, which likely contributes the sound and may have originally suggested a ritual or invocation. The exact historical development of 且 in this context is uncertain.
Words 言 that bring harm, like a sharp tool 且: imagine someone using cutting words to place a curse.
For ソ, picture a curse so strong it feels like a sudden, sharp 'so!'—the sound of a curse hitting its target: so -> ソ.