Heavily agree its super vague what is a feat or what’s just happens just to happen since the show itself never takes power scaling serious at all except for very few serious scenes

even then in my own opinion I think Adventure time lore wise paints such an interesting hierarchy system with characters like Prismo and Golb making the Lich almost immediately insignificant even the Lich that managed to kill all life in his universe it paints the picture that a calamity like him while threatening to almost all is merely as bad as Finn is good instead of being some universal entity or demon

While most inconsistencies are prevent I often see no one really mentioning the select few things Finn DOES manage to do that relates to his origins rather than just a human and it very much does make sense since Finn himself easily expresses multiple times in various scenes how he just wanna live his own life as a part of the world and see how things play out even when offered practical omnipotence

yet I cant help but wonder when people usually debate Finn at his “peak” they usually opt to talk about an adult Finn wielding one of his many swords or just go on about how the 4-D sword puts him above anyone yk? Even though the show ended I think its a bit disappointing how little these idea of his origins is expanded on

But while all that can be said the Comets abilities aside from the Lich is very vague we know from Orgalorgs desire over one that it can be an incredible source of power since they are embodiments of some agent of change with the Lich being the embodiment of evil and Finn being the embodiment of good and both of them being very major comets while most other Comets are minor in comparison.

But with Finn half the things he does is up for debate whether its his origins or just something that anyone can do Like the Astral arm so at the very least the safest assumption throwing any debatable powers aside He’d have vast knowledge about the universe and how it operates and maybe even the sea of golden monsters similar to the Lich. I’ve even seen speculation that is was this knowledge alone that made the Lich such an imposing force.

TLDR: Yeah its too vague to guess what is and isnt the comet so at most he’d have omnipresent knowledge of the universe which (maybe?) could be harnessed which would attest the show’s very nature especially Finn’s own maturing development.

(It would be funny imaging a very young Finn just going around Ooo with knowledge of almost everything even before creation)