Luke wondered if he hadn't gone insane after all those fights. He had thought that he had become a survivor, after all, that mess. Still, it seemed that he had become a scientist instead of trying to understand how the organs of monsters worked. While he was in that dimension, he went as far as dissect his own summoned monster to understand how the heck their bodies worked.
In the end, Luke succeeded in making the weapon that he wanted, but it was rather limited since he couldn't make a sword that could eat monsters. It would take too long, after all. Waiting for the digestion process was too troublesome, as well, and the sword would have to throw away many parts of the monster's body. So, Luke made it work by draining the monster's blood. The sword came with some limitations thanks to that, so it couldn't make his skills level up, but it could increase his parameters.
Essence Sword