Exoskeletons have 4 variants: saturation, movement, battery, and defense. They can be equipped by interacting with them. You can only have 1 of them equipped at a time. You can charge them by standing on a draconic infuser and you can check the charge with a draconium battery. Exoskeletons are required for the swords and cannons that are also crafted in this mod to have their special abilities and using them will decrease the charge of the exoskeleton.