brilliant red, glowing
煒 centers on a vivid, radiant glow, especially a brilliant red light. It describes something shining brightly with warmth and intensity.
煒 combines 火 (fire) with 韋, which likely contributes the sound. The character expresses the idea of a bright, glowing fire.
Fire 火 on the left and 韋 on the right: picture a blazing fire that glows with a brilliant red light, so intense it seems to radiate heat.
For イ, imagine the glowing fire is so bright it makes you say 'Eee!' in awe: 'Eee!' -> イ, as the brilliant red flames shine.