excellent horse, noble steed
駔 centers on a horse of exceptional quality: an excellent horse or noble steed. The two given meanings are essentially synonymous, both describing a superior mount.
駔 combines 馬 (horse) with 且, which likely contributes the sound. The exact historical development of the compound is uncertain, but the structure suggests a phono-semantic character for a type of horse.
The left side is a horse 馬, and the right side 且 looks like a shelf or a stand. Imagine a noble steed displayed on a pedestal, showing its excellent quality.
For ソウ, picture a soulful, excellent horse: soul -> ソウ. The noble steed has a deep, soulful presence.