needle
鉥 centers on a needle, specifically a long needle used in acupuncture or sewing.
鉥 combines 金 (metal) with 术, which likely contributes the sound and relates to a long, pointed object. The exact historical development is uncertain.
The left side 金 is metal, and the right side 术 looks like a long, thin tool. Picture a metal needle used for precise work.
For ジュツ, imagine a jeweler using a long needle to set tiny gems: jeweler's tool -> ジュツ.