This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
The exact historical development of 靗 is uncertain. It visually combines 青 and 光, but the original semantic and phonetic roles of these components are unclear.
Since the meaning is unclear, focus on the shape: 青 (blue) and 光 (light) together suggest a blue light, but this is just a visual mnemonic, not a real meaning.
For テイ, imagine a blue light forming the letter T: T -> テイ, tying the shape to the reading.