The Skill system in Dragon Quest 8 is pretty simple. Every time one of the four characters levels up, he or she acquires a few skill points, which the player immediately allocates into one of five skills. Each of the four characters has a unique list of skills, based on the weapons the character can equip with an additional skill based on a distinguishing characteristic of each character. For example, the main hero has the Swords, Spears, Boomerangs, Fisticuffs (unarmed combat, shared by all four characters), and Courage skills. Once a character put enough points into a skill, the skill levels up, and the character either acquires a new ability or spell, or the character's power with that certain weapon increases.
Of course, it is impossible for one character to max out all five of his or her skills. Right now, I am expecting to have accumulated around 200 skill points for every character by level 40 or so. Since it takes 100 skill points to max out a skill, a character can expect to only max out two skills during the game. Maybe three if the player reaches really high levels. So, I have been focusing each of my characters on only one or two skills during this go-through of the game. For example, my main hero is currently focusing on the Swords and Courage skills.
What I really like about this system is that it gives the characters some degree of flexibility. For example, if a player has Jessica (naturally the game's main attack mage) study the Knives skill, she acquires potent single-target physical attacks, and eventually gains the ability to equip high-attack power swords. If Jessica focuses on the Whips skill, she gains multi-enemy attacks that induce status conditions. If Jessica focuses on the Staves skill, her magical powers increase and she acquires healing abilities. So which skills a character focuses on can have an enormous impact on how the character fights in combat.
On of the benefits of this customization system is that the game can play very differently if a player chooses a different selection of skills. Even though I haven't even finished the game yet, I am already strongly tempted to play through Dragon Quest 8 again, just to try out a different combination of skills. Of course, this system does have a big downside: this degree of flexibility does allow a player to gimp his characters. In my first attempt at playing Dragon Quest 8, I tried to improve all of my characters' skills evenly. As a result, my characters only gained useful powers at a painfully slow pace, and they would have never acquired everything.
Finally, one of the major elements of this customization system I like is how limited in scope it is. It is not an incredibly deep customization system that lets the player give any ability to any character. Because of that, the four characters maintain a strong sense of individual identity and uniqueness. Also, because the characters always gain important powers such as healing magic regardless of which skills the individual characters take, no character is required to take any specific skill. Many of the team's bases are already covered, so it is hard to gimp the team as a whole.