the millipede sometimes confounded with the grow-worm, bright, clear
蠲 is a rare kanji with two distinct meaning clusters: a millipede-like creature, and the abstract quality of brightness or clarity. The connection between these senses is unclear, so treat them as separate ideas.
The exact historical development of 蠲 is uncertain. It visually combines 益 and 蜀, but the original semantic and phonetic roles of these components are not clearly established.
The left side 益 suggests benefit or increase, and the right side 蜀 is a caterpillar-like shape. Imagine a beneficial millipede that clears away debris, making things bright and clear.
For ケン, picture a bright millipede named Ken who clears paths: Ken -> ケン, and his many legs sweep everything clean.