This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鎕 combines 金 (metal) with 唐, which likely contributes the sound. The exact historical development is uncertain.
The left side is metal 金, and the right side is 唐. Without a clear meaning, picture a mysterious metal object from the Tang dynasty: its purpose is uncertain.
For トウ, imagine a metal 金 object from the Tang 唐 dynasty: Tang -> トウ.