I figured that might be the case (use X or Z) to equip different skills but it does not work for me. Pressing X does not trigger the skill description prompt.
ahhh I see the confusion. This was an intentional choice due to time limitations, but currently, the first ability is always equipped to the Z action when starting a run. This is because when you enter the "start run" doorway, the ability is actually equipped, and not in the "ability-select" room. I'll add some sort of check for this in the future so that you can equip it to whichever slot you like! Maybe make the "interact" button different from the "action slot 1" button too.