SOLVED. YA Fantasy series? It includes another world or dimension with "monsters" and "God". As well as bat like creatures and a secret society sworn to protect the mortal realm. [s]

[Chris]

These descriptions aren't chronological just plot points I remember.

There was a girl practicing martial arts on a wooden cross with the purpose of deadening the end nerves to hit harder.

The best sword maker in the book made his swords from pigeon poop.

After one of the characters travels through the portal/other world or whatever it is, he meets "God" the one responsible for creating humans. He says something like yeah I upgraded your body while you were out and made a"2.0" body.

Towards the end of the book he meets a turtle like creature that the universe rests on or something like that and tells it off something like "you gods get bored and then screw with us mortals"

At some point the character also discovers some kind of goo that feeds baby demons and after the upgraded body it's better than regular food.

[Becca]

The Black Tattoo by Sam Enthoven looks like a match. Google Books Preview: https://www.google.co.uk/books/editio...

[Chris]

I do believe that's it. Thank you!