inaccessible place, impregnable position, steep place, sharp eyes
嶮 centers on steep, inaccessible terrain that is hard to approach or attack. The sense of sharp eyes extends this idea to a piercing, unassailable gaze.
嶮 combines 山 (mountain) with 僉, which likely contributes the sound and the idea of sharpness or steepness. The exact historical development of 僉 is uncertain, but the mountain component clearly anchors the meaning to rugged terrain.
A mountain 山 with a sharp, complex right side 僉: imagine a steep, jagged peak that is nearly impossible to climb, and from its top, sharp eyes survey the inaccessible land.
For ケン, picture Ken (a person) standing on a steep, impregnable mountain, his sharp eyes scanning the horizon: Ken -> ケン.