majestic
咺 centers on a sense of majesty or awe-inspiring presence, often associated with a commanding or dignified demeanor.
咺 combines 口 (mouth) with 亘, which may contribute a phonetic element. The exact historical origin is uncertain, but the character likely relates to a commanding or majestic vocal expression.
A mouth (口) that speaks with the authority of something enduring (亘) creates a majestic presence.
For ケン, imagine a majestic Ken doll standing tall and speaking with authority: Ken -> ケン.