Arcana is the study of magic from the perspective of the mathematics and occult, and the skill of Arcana represents how well versed a character is in handling, scripting and understanding it.
Dexterity
The Dexterity Arcana skill can be used handle the etching of runes, making of effigies, other craft relating to the arcane.
Awareness
The Awareness Arcana skill can be used to sense aura of magic around you, whether it suffuses the atmosphere and terrain or are spell secreted away somewhere nearby.
Intelligence
The Intelligence Arcana skill represents your recall of arcane knowledge and your understanding of it.
Instinct
The Instinct Arcana skill is the ability to communicate and understand Arcane spirits, those that represent abstract concepts or those to do with the soul.