Cleric enhancements (history)

Level 1

 * Devotion I: grants a 20% increase to the effectiveness of 1st level healing spells
 * Divine Vitality I: Activate to restore a small amount of mana to another character. Consumes a use of turn undead for the day.
 * Energy of the Zealot I: grants 20 additional spell points
 * Extra Turning I: grants 2 additional turn undead attempts before resting.
 * Negation I: grants a 20% damage increase to 1st level negative healing spells
 * Skill Tactics I: +3 on Diplomacy and Concentration checks
 * Skill Recovery I: +3 on Heal and Repair checks

Level 2

 * Energy of the Zealot II: grants 30 additional spell points
 * Divine Cleansing I: +2 to a friend's Fortitude save, takes 1 turning
 * Improved Devotion I: grants a 30% increase to the effectiveness of 1st level healing spells
 * Improved Negation I: grants a 30% damage increase to 1st level negative healing spells
 * Cleric's Wisdom I: +1 Wisdom
 * Improved Empower Healing I: reduces spell cost increase of Empower Healing from 50% to 33%
 * Improved Recovery I: increases the effect of healing spells cast on you by 10%

Level 3

 * Energy of the Zealot III: grants 40 additional spell points
 * Devotion II: grants a 20% increase to the effectiveness of 2nd level and lower level healing spells
 * Negation II: grants a 20% damage increase to 2nd level and lower level negative healing spells
 * Skill Tactics II: +4 on Diplomacy and Concentration checks
 * Skill Recovery II: +4 on Heal and Repair checks
 * Divine Healing I: casts a heal-over-time on a party member, takes 1 turning

Level 4

 * Energy of the Zealot IV: grants 50 additional spell points
 * Improved Devotion II: grants a 30% increase to the effectiveness of 2nd level and lower healing spells
 * Improved Negation II: grants a 30% damage increase to 2nd level and lower negative healing spells

Level 5

 * Cleric's Wisdom II: +2 Wisdom
 * Devotion III: grants a 20% increase to the effectiveness of 3rd level and lower level healing spells
 * Divine Vitality II: Activate to restore a small amount of mana to another character. Consumes a use of turn undead for the day. Note: the exact level at which this enhancement is obtained has yet to be confirmed.
 * Energy of the Zealot V: grants 60 additional spell points
 * Negation III: grants a 20% damage increase to 3rd level and lower level negative healing spells
 * Skill Tactics III: +5 on Diplomacy and Concentration checks

Level 6

 * Energy of the Zealot VI: grants 70 additional spell points
 * Improved Devotion III: grants a 30% increase to the effectiveness of 3rd level and lower healing spells
 * Improved Negation III: grants a 30% damage increase to 3rd level and lower negative healing spells

Level 7

 * Energy of the Zealot VII: grants 80 additional spell points
 * Devotion IV: grants a 20% increase to the effectiveness of 4th level and lower level healing spells
 * Negation IV: grants a 20% damage increase to 4th level and lower level negative healing spells
 * Skill Tactics IV: +6 on Diplomacy and Concentration checks

Level 8

 * Cleric's Wisdom III: +3 Wisdom
 * Energy of the Zealot VIII: grants 90 additional spell points
 * Improved Devotion IV: grants a 30% increase to the effectiveness of 4th level and lower healing spells
 * Improved Negation IV: grants a 30% damage increase to 4th level and lower negative healing spells

Level 9

 * Energy of the Zealot IX: grants 100 additional spell points
 * Devotion V: grants a 20% increase to the effectiveness of 5th level and lower level healing spells
 * Negation V: grants a 20% damage increase to 5th level and lower level negative healing spells
 * Skill Tactics V: +7 on Diplomacy and Concentration checks

Level 10

 * Energy of the Zealot X: grants 110 additional spell points
 * Improved Devotion V: grants a 30% increase to the effectiveness of 5th level and lower healing spells
 * Improved Negation V: grants a 30% damage increase to 5th level and lower negative healing spells

Unconfirmed
The following enhancements appear in the game data files but their implementation has not been confirmed yet:
 * Charisma I and II
 * Divine Cleansing II and III
 * Divine Elemental Smiting I, II and III
 * Divine Healing II and III
 * Divine Light I, II and III
 * Divine Outsider Smiting I, II and III
 * Divine Vitality III and IV
 * Extra Turning II and III
 * Improved Empower Healing II and III
 * Skill Recovery III, IV and V