1. Armor, by its nature, closes the character off from the world around him and therefore affects using Arcana.
  Specifically, it makes fatiguing arcana harder to use without exhaustion.
Whenever a character uses an arcana that is fatiguing while wearing any kind of armor, apply a modifier to the TN for the Willpower (Self-Control) check. If the character is wearing armor in which he is not trained, the penalty is doubled.
Using arcana that does not cause fatigue is not affected by armor.

Table 1a. Arcana Fatigue Penalties by Armor Type
Armor TypeTrainedUntrained