Since I couldn't find this info anywhere else, I thought I might post it here. I found the ranks (or sometimes referred to as Skill Levels) for the enemies in FF2 for the NES. In the rom, they're located from offset 17710 to 1778F, 1 byte per enemy. Since there are different translation versions of the NES rom and I'm not sure whether the offsets are the same in each version, I thought I'd post a picture of it so everyone can search for the byte sequence if need be.

The enemies are in the same order as in the Jade editor, so for example the first byte is LegEater's rank, the second byte is Vampthorn's rank, and so forth. By playing around with these you can change the number of uses needed to level up weapons/spells. It always bugged me that in the original game, weapons and spells could hardly increase beyond level 8 due to the way the skill point system works. Reaching the maximum of level 16 was pretty much impossible since no enemy in the game has a higher rank than 7. Anyway, I hope this information is useful to some of you.