handle
鉉 centers on a handle, specifically the handle of a cooking vessel or pot. The meaning is concrete and narrow, referring to a metal lifting handle.
鉉 combines 金 (metal) with 玄, which likely contributes the sound. The character originally referred to a metal handle for lifting a tripod or cauldron.
The left side is metal 金, and the right side 玄 looks like a sturdy loop. Picture a metal loop handle on a heavy pot: 鉉 is that handle.
For ケン, imagine Ken the blacksmith forging a metal handle: Ken -> ケン, and he lifts the pot by the 鉉.