Attributes

Overview
Wisdom, Intuition, Agility, Strength.

These four attributes are used to calculate bonuses for all other skills. Each Skill or Spell is based on three of the attributes. The actual calculation involves adding the 3 attribute  mods together and dividing by 5.

Thus the formula becomes: Skill base + (Attr1 + Attr2 + Attr3) / 5 + Magical Modifier.

Profession bonuses are added to the Base Attributes and the resulting increases affects al l other skills / spells
 * Master DW/LW gets a 15 point increase to Base Attributes which translates into a (15+15+15)/5 = 9 point increase in skills / spells

Max Mods source for more detailed info
 * Master CW/Demon Hunter gets a 30 point increase to Base Attributes which translates into a (30+ 30+30)/5 = 18 point increase in skills / spells

Mages Warriors: Seyans: Professions which boost your base attributes are added after bless/gear and do not seem to count toward the normal cap.
 * Attributes: 200% base
 * Skills: 150% base + attribute bonus
 * Attributes: 150% base
 * Skills: 150% base + attribute bonus
 * Attributes: 172% base
 * Skills: 172% base + attribute bonus