i have been doing some leveling and noticed a pattern with the magic and weapons leveling, each time you level up the times you need to use said weapon or spell increases by 10. You start at the first level requiring 10 uses before level up, once you level up, the second level requires 20 uses before level up, this system can be used to keep track of how many times a weapon or magic spell must be used before level up, the higher the enemy rank, the more points from use such as using a level 6 sword level once while in battle with a black knight will grant 6 points since 6 is the black knights rank, it acts just like level 1 as 6 times 10 is 60, which is how much uses is required for level 6, the original final fantasy 2 required 100 uses for every level but eventually you need to go to higher ranks to get the levels you need, dual wielding doubles points for weapons, but people prefer to use the target cancel bug instead on the nes version. So if you follow said pattern, you might be able to know how many times to cast a spell in combat to level it up the way you desire.

A great way of leveling is to go to the outside of salamand after the cyclone has appeared, the enemies will be replaced by stronger enemies like sergeant, captain, sorcerer, hill gigas and bombs. Use the magic spell you desire individually on each target during battle, higher levels are harder to gain because the level of the weapon or magic spell removes gained points in combat. individual targeting will add the points of every enemies rank and the game will have no choice but to give points, the enemies near salamand usually appear in groups of 5-8, making it easy to get points by casting spells individually, you can use this advice to get any spell to level 16