blaze
燬 centers on a strong, destructive fire: a blaze that consumes or damages. The single given meaning 'blaze' captures this intense burning.
燬 combines 火 (fire) with 毁, which likely contributes the sound and the idea of destruction or damage, together suggesting a destructive fire or blaze.
The fire radical 火 beside 毁 (which suggests breaking or destroying) creates the image of a fire that breaks everything down: a fierce blaze.
For キ, imagine a key-shaped flame unlocking a destructive blaze: key -> キ, and the fire spreads wildly.