make fire by rubbing sticks
鑚 centers on the act of creating fire through friction, specifically by rubbing sticks together. It is a specialized character for this ancient fire-starting method.
鑚 combines 金 (metal) with 賛, which likely contributes the sound. The character is associated with a metal tool used for drilling or friction-based fire-starting, but the exact historical development is uncertain.
The left side 金 suggests a metal tool, and the right side 賛 looks like a complex arrangement of parts. Imagine a metal drill-like stick being rubbed vigorously against wood to create fire by friction.
For サン, picture the sun (サン) being born from the fire you create by rubbing sticks: sun -> サン, and the fire-starting tool brings light like the sun.