ARR and Beyond!

[Niwashi]

Pretty sure it's +50% exp for any job lower than your highest, regardless of what the gap might be.

Up to level 60, the armoury bonus is 100%. Then from level 60 to 70, it's 50%. It doesn't depend on the amount of the level gap in either case, just on the level of the class you're currently advancing.

- when fighting enemies of much lower level, the boost is higher but the actual EXP is lower. From attacking the same Lv7 enemy, the Lv9 class received "223 (+180%)" EXP and the Lv16 class received "51 (+230%)" EXP. So the bonus can make it sound more impressive but actually you're getting less out of it.
...
- my lowest class is Lv55 and got +170% EXP, I think this includes 15% from FC boost and 50% rested bonus, leaving 105%? It seems an odd amount.

It sounds like some other bonus may have been involved as well. Were you attacking multiple mobs? If you get several kills in quick succession, there's a chain bonus that adds to it after the first one, though I'm not sure what the amounts are on that.