[Er1c2]

When you level up you get a random ammount of experience added to your character. When you level up a particular type of experience, sometimes you will get a benifit from it (more SP, lower WC, etc.).

Where the experience goes after killing something depends on which skill you have readied (which means, for example, that sorcerers can cast a spell, turn on their sword, and get physique experience). Say /skills to see your list of skills.