When you create a generic unit you get points to spend on their STATS. The point value ranges from -5 to +10 and is a direct result of the mana cost to create a unit.
Each class type has preset aptitudes, or how much each stat grows upon leveling up, and with gear (iirc).
Each class has 6 tiers, each tier is unlocked through leveling up a class. So a level 1 tier 1archer needs to level up to unlock the tier 2 archer. Each new tier increases the aptitude of the unit.
You can permanently increase aptitudes by placing a unit, or units, in the Weapon Mastery Dojo (WM). Aptitudes cap out at 300% for all units.
Reincarnating resets your level to 0, but stores some of your stats. The amount stored depends on the reincarnation type (Genius gives the most), as well as growth correction (% based on stored levels - caps at 1000%) and stored levels.
Continuous reincarnations give more stats to assign upon reincarnating, capping so that you can assign 255 in each stat. --- XBL: Darth Vandale, PSN: gvandale Battle.net: Gvandale#1921
When you level up, the game increases your stats by a % of your level 1 stats without equipment (about 40%). So if you have 255 stat points you will obviously gain more stats upon level up than if you had 30.
Growth correction then adds to that, by increasing the level up gain by up to 400% normally or up to 10,000% in Rasetsu mode.
To increase the Growth correction, just reincarnate, the more you reincarnate, the higher it gets.
To increase the number of bonus points you get, the points you assign to your stats, then that is based on your stored levels. The higher your stored levels, the more bonus points you have. Normal max is 200 points gained from stored level + 10 from reincarnating at genius. With Rasetsu mode on you can gain much more stored levels, enough to get 255 in every stat, which combined with the 10,000% growth correction, you will max every stat (99,999,999 attack etc, and 99,999,999,999 HP and SP, basically the same max as the LoC bonus) by level 9999.
Aptitudes are increased by putting the character in the right dojo (the description will say that it increases aptitudes) and you have to clear a map to get a chance to get a boost. So running through the IW gates will not allow you to get any aptitude points, but killing all the enemies will. --- http://s7.zetaboards.com/Burnin_Rubber/index/