I'm pretty sure that almost everyone has read or heard about folklore stories. You know, about tales, legends or mythical scenarios that science cannot explain. Some of these stories have been around for thousands of years already and have been published on some books. Some of these stories are made to protect a certain landform or a body of water just to keep people away from destroying an earthly landmark. Some even grant wishes as a prize for something, an example of this is the Leprechaun folklore.
Going back to the anime. For me, I see Felia as one of those characters on folklore stories. She's an angel and a guardian at the same time of the planet. Felia is indeed a representation of the setting of this anime series.
Felia's disappearance on the final episode as a heroine is kinda sad yet brought acceptance to its anime viewers. Her disappearance may or may not be a mystery to its anime fans, it is an open-ended story though but something tells me that this original anime series cannot have another season. The ending credits and clips are just too much as spoilers for the hopeful fans like me.
Let's just hope for the best though as 8-bit animation studios has some successful projects with trailing seasons. Still, in the end, it is all about the sales. Will Comet Lucifer have a second season?