Stats skills are necessary for the advancement of all types of characters be they fighters, archers, casters or crafters. You gain active experience in these skills by killing creatures near that of your own level. All Stats skills must be raised actively, by fighting monsters and gaining experience points directly from the monster's defeat. Your character level is the average (rounded down) level of your Melee, Magic, Defense, and Recovery skills. You receive no experience point penalty for raising any of these four skills above your character level, as they themselves determine your character level. However the other Stats skills (e.g. Stat Enhancement) will receive a penalty if leveling at or above your character level.