API IsPassiveSpell

Returns true if the specified spell is a passive ability. isPassive = IsPassiveSpell(spellId or index, bookType)

• spellId: - spell ID to query.

• index: - spellbook slot index, ascending from 1.
• bookType: - Either BOOKTYPE_SPELL ("spell") or BOOKTYPE_PET ("pet"). "spell" is linked to your General Spellbook tab.

• isPassive:Flag : 1 if the spell is passive, nil otherwise.

• With my Human Paladin, here are the "spells" I found to be Passive:
• Block (Passive)
• Diplomacy (Racial Passive)
• Dodge (Passive)
• Mace Specialization (Passive)
• Parry (Passive)
• Sword Specialization (Passive)
• The Human Spirit (Racial Passive)