Recommended: Mindread, Wisdom, Lockpick.
Increase the skills connected with the weapon you use the most/prefer.
Notice: In the beginning you can raise your skills to level 5 max. Once you have the obtained the Battle Tower, your trainer will allow you to raise your skills up to level 15.
Increases the damage dealt while unarmed - completely useless.
Single-Handed Weapon Expertise
Increases the damage done while fighting with a single weapon.
Increases the damage done while fighting with two weapons.
Sword and Shield Expertise
Increases the damage done while fighting with a weapon and a shield.
Two-Handed Weapon Expertise
Increases the damage done when attacking with a two-handed weapon.
Lowers the amount of experience points you have to spend on reading someone's mind - very useful.
Increases the amount of experience gained - very useful.
Lets you open chests with higher security. It's useful if you want to open every chest you come across.
Increases the capacity of your backpack - useful in the later part of the game, when you'll be running out of space, although only till you gain the Battle Tower, which provides you with a chest capable of holding 400 items.