Lightning is a metaphor for human emotions such as: Fear, Reverence, Creativity, etc. In essence, lightning ignites our deeper selves. These bolts of energy can potentially tap into our most primal, basic emotions. The celtic people understood this, and often went to places where lightning struck, calling them holy and the place to contact unfathomable powers. A bolt of lightning is a symbol of loss of ignorance. It also represents the punishment of humans from the Gods. Below is a quick list of symbolic meanings of lightning:
⚡ Power
⚡ Clarity
⚡ Sacred
⚡ Fertility
⚡ Creativity
⚡ Revelation
⚡ Inspiration
⚡ Destruction
⚡ Enlightenment
⚡ Announcement

I think Yuan is related to lightning because he has lost his ignorance. Before traveling with Mithos, Martel, and Kratos, Yuan was just another warrior who hated elves and humans alike. He never understood why there was so much hate for half-elves, so he became racist against others. When Martel opened his eyes to loving all, he lost his ignorance and he lost his hate. This also can relate to the term above, clarity. He became aware of a vision for all types of people to live in peace together, instead of separating from one and other. He had a revelation that humans, elves, and half elves could be in a world together if they worked on it, and had an end goal in mind. This is why he fought so hard against Mithos and Kratos, because he wanted Martel's love and affection to be spread, not hate. Because Yuan is technically an angel as well, he is able to take his lightning powers and punish others with it, where he still punishes those who don't agree with him. Overall, lightning is a good symbol to be attached with Yuan because of all of the comparisons he has to the symbolism.

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