Uniques are special traits that help you better define your character and set them apart from everyone else. Everyone is unique, though ninja take a person's special talents and qualities one step further, developing them into useful aspects of the character. With few exceptions, you may only select uniques at creation. They represent your character's inherent abilities or nature or a cornerstone of your character's training.
At creation you gain two Physical Uniques, two Spiritual Uniques and a single Core Unique. You may choose to give up two uniques to gain an extra unique in any category. So you could trade in two physical uniques for a core or spiritual unique. Or you may trade in a spiritual unique and a core unique for another physical unique. So forth and so on. Remember, most clans start with fewer uniques then normal and may force you to make certain unique choices. See individual clan entries for details.
In addition to their effects, all Physical and Spiritual uniques have two 'favored stats' each. You gain a +2 bonus each favored stat at creation. You gain another +1 bonus to each favored stat each time you level up. If you gain the same stat favored multiple times then these bonuses stack