This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 銟 is uncertain. It visually combines 金 (metal) on the left with 山 (mountain) above 巾 (cloth) on the right, but the original semantic and phonetic roles of these components are unclear.
Since the meaning is uncertain, focus on the shape: metal (金) beside a mountain (山) over cloth (巾). Picture a metal tool used to shape mountain cloth, but remember the meaning is unclear.
For サ, imagine a saw (サ) cutting through the metal and cloth parts of the kanji: saw -> サ.