The Devouring Body Supreme Metac and its ability to grant him the power of the beings he eats gave him the idea that he could use it to make up for discarding the elemental Metacs. But he couldn't use it directly as it was a Supreme Metac, so the first step was cutting down its 3-D form and crippling it into a 2-D version.
During the process, he had to cut away a lot of abilities and features of the original. But he tried to maintain the core characteristics that he was interested in. The core being its ability to take the power of what it ate. However, how much power could be gained from eating and how that power could be used had to be changed.
The 2-D version of the Devouring Body Supreme Metac he created wasn't as powerful as the original, since it couldn't take the form of a celestial weapon acting as an external source of power. It would need to change the user's body directly, the way he changed his body with the body-refining Metacs of the Forging.
