In a non-representational simile, the common element can be one independent quality, even if explaining it takes several words. In tamthīl, the quality is abstracted from the relationship among several components.
“Zayd is brave like a lion” — courage is a single respect.
“Swords flashing in clouds of dust are like falling stars in a dark night” — a structured scene is the respect.
Al-Sakkākī’s treatment includes terminological subtleties; not every later phrasing of tamthīl should be imposed without qualification. The governing pedagogical criterion remains the actual nature of the shared image.