You can learn many things. I learned:
Not to mess with wolves that have swords on their backs.
That spawning explosive barrels and saw blades in a room, and setting the barrels off with a well placed shot can clear rooms faster than you can say "Oh Noes!"
That Sephiroth is a push-over when you have maxed you Glide, High Jump, Air Dodge, and the other skill.
That small dinosaur things are resistent to everything.
That Oh My God Adoring Fans are annoying. "By Azura by Azura by Azura!"
That, regardless of however high of a level your opponent is, a Quickening chain will turn them into tiny dust particles.
That it is perfectly OK to hit other drivers into busses.
That no matter what you do, how hard you try, you will NOT be as cool as a final boss. Unless the boss is Yami.
That keys ARE lethal weapons.
That Hades hath spinning pillars with blades. And they will cause you many re-deaths.
That there is no death as long as you have enough sand.
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I could probably think of more, but I'm too busy playing Okami.