This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
嵢 combines 山 (mountain) with 倉, which likely contributes the sound. The exact historical development is uncertain.
The kanji has 山 (mountain) on the left and 倉 (storehouse) on the right. Imagine a mountain storehouse, but its exact meaning remains uncertain.
For ソウ, picture a mountain storehouse filled with souls (ソウ) of ancient travelers. The sound 'soul' cues ソウ.