The skills used in physical combat:

melee- A player's mastery of hand to hand combat.
attack- A player's mastery of weapon combat.
defense - A player's mastery of the arts of self-defense.
double wielding- A player's mastery of combat with two wielded weapons.

fighters try to master all fighting skills
monks try to master some fighting skills
rogues try to attain a degree of mastery over many fighting skills