I typically don't worry about HP and MP when leveling. At the end of the game when your characters are level 99 they will be very close with numbers like 9732 hit points or so and 984 magic points. If you're real concerned about getting max HP and MP just do some math and see how many HP and MP you get for a level and see how much you're going to be off by and equip Either Bahamut or Crusader for the number of levels needed to offset it. Also, remember that you'll get more HP and MP in the later levels, so try to do the HP and MP boosts later on when you'll get more out of them.