Eisen felt a little bit uncomfortable that the others were fighting while he just stayed in the dungeon to work on ranking his skills up some more, but that was simply the most important thing he had to get done right now.
To get started, Eisen was trying to work on something that let him gain a little bit of proficiency for two of his skills. Truth-seeing eyes and drawing. Since Eisen's visual crafter's mind abilities were connected to his truth-seeing eyes, whenever he used those abilities he gained proficiency for that skill as well. And since he needed to see the blueprints in front of him using visualization to properly transfer them to paper with his drawing skill, it was a pretty good combo for now.
His truth-seeing eyes skill was very close to ranking up already, it was actually at level 99, but the skill was a pretty high-tier one so it took longer to level it up than other skills. Especially the hurdle of leveling it up from level 99 to 100 was huge.