Wisdom

The wisdom parameter is used as an indication for the intuition and common sense of a person. Wisdom gives you more knowledge, which results in more experience that can be gained.

Who should use it ?

Everyone benefits from wisdom. It gives you a bonus to experience points that can be gained.
For the nameless One, wisdom also means that more memories can be regained, which always means extra experience and thus extra gameplay.
As a mage a higher wisdom increases the number of spells that can be cast.

The Nameless One

At the end of the page the table is given that indicates what the effect is of increasing the wisdom parameter. From this table you can see that the bonus to the spells start at 13 and the knowledge bonus at 15.

The Nameless One starts out with a value of 9 for the wisdom parameter. Independent of the class I think that you should increase this value to at least 13. You still have the possibility to increase this even further in the game. If you are a mage than set it to 15.

The Tables

The following table lists the modifications that are applied to one's abilities given a certain wisdom.