ConstructionRelevant featurePoint about wāw
وَأَنْتُمْ تَعْلَمُونَPronoun as subject, verbal predicateExplicit circumstantial connection
وَهُوَ مُسْرِعٌBearer's pronoun as subjectCase for and against mandatory wāw
عَلَى كَتِفِهِ سَيْفٌPreposed prepositional phraseReason to omit wāw
كَأَنَّمَا ...Comparative particle supplies a linkCohesion without a separate wāw
Each row contains a different rationale. Reducing them all to “wāw is optional with nominal ḥāl” would obscure the technical distinctions.