This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鋻 combines 臤 (possibly a phonetic component) with 金 (metal). The exact historical development is uncertain, and the character is rare.
鋻 has 金 (metal) below 臤. Without a clear meaning, picture a sturdy metal tool being pulled from a container (the 匚 shape in 臤) — perhaps a blade or implement.
For ケン, imagine a metal (金) tool named Ken: Ken -> ケン, and the tool is pulled from the upper part like a sword from a sheath.