Secondary Skills are qualities of your hero. There are 14 different secondary skills and each one has three levels: Basic, Advanced and Expert. When your hero gets a level-up (primary skill increase) he/she also gets a choice of 2 secondary skills - you may choose to learn one. Hero can have a maximum 8 secondary skills learned. After hero has learned a skill, learning it again will increase it's level. If hero manages to get all 8 expert skills, future level-ups will only give a primary skill increase.

Secondary
Skill
DescriptionBasic level
Advanced level
Expert level
Archery SkillIncreases the damage of range striking units in hero's army.
Removes 50% penalty for shooting past objects (castle walls).
+10% Damage
+25% Damage
+50% Damage
Ballistics SkillIncreases the catapult's shots, damage and accuracy in seige combat. 1 shot + extra dam
2 shots + extra dam
2 shots + max dam
Diplomacy SkillWith Diplomacy skill army camps will sometimes offer to join your army.
Percentage shown is the percentage of monsters in the stack.
25% join
50% join
100% join
Eagle Eye SkillYour hero gets a chance to
learn spells that have been cast against him/her in combat.
20% 2nd level max
30% 3rd level max
40% 4th level max
Estates SkillHero generates money each turn. 100 gold/day
250 gold/day
500 gold/day
Leadership SkillIncreases hero's morale.
Necromancers can't learn this one.
+1 morale
+2 morale
+3 morale
Logistics SkillHero gets an extra land movement. +10% movement
+20% movement
+30% movement
Luck SkillIncreases hero's luck. +1 luck
+2 luck
+3 luck
Mysticism SkillIncreases rate per turn in which hero regenerates mana. 2 mana/turn
3 mana/turn
4 mana/turn
Navigation SkillHero gets an extra movement on water.
If map has no water, the skill is useless.
+50% movement
+100% movement
+150% movement
Necromancy SkillAnimates a portion of the units killed in battle into skeletons when you win.
Available only to Necromancer and rarely to Warlock.
10% of killed units
20% of killed units
30% of killed units
Pathfinding SkillReduces the movement penalty on rough terrains.
(Beach, Cracked land, Snow, Swamp, Desert)
If map has no rough terrains, the skill is useless.
-25%
-50%
-100%
Scouting SkillIncreases hero's visible area in adventure window. +1 square
+2 squares
+3 squares
Wisdom SkillAllows hero to learn spells higher than 2nd level. 3rd level spells
4th level spells
5th level spells


I suggest you learn these secondary skills as I consider them the best for each hero type.
Some of these proposed skills might turn useless due to map conditions (Navigation, Pathfinding)
Secondary Skills in bold are the skills that all heroes of that type have from the start.

Knight - Ballistics, Diplomacy, Leadership, Logistics, Luck, Mysticism, Pathfinding, Wisdom
Barbarian - Archery, Ballistics, Leadership, Logistics, Luck, Mysticism, Pathfinding, Scouting
Sorceress - Archery, Diplomacy, Estates, Leadership, Luck, Mysticism, Navigation, Wisdom
Necromancer - Eagle Eye, Estates, Logistics, Luck, Mysticism, Necromancy, Pathfinding, Wisdom
Wizard - Archery, Eagle Eye, Estates, Leadership, Logistics, Luck, Mysticism, Wisdom
Warlock - Ballistics, Eagle Eye, Estates, Leadership, Luck, Mysticism, Scouting, Wisdom


This table shows a chance for each secondary skill to be learnt by heroes.
Higher the number = bigger the chance ; 0 = no chance ; Highest chances for each skill are in bold.

SKILL
Barbarian
Knight
Necromancer
Sorceress
Warlock
Wizard
Archery
3
2
1
3
1
1
Ballistics
3
4
3
3
3
3
Diplomacy
2
3
2
2
2
2
Eagle Eye
1
1
3
2
3
3
Estates
2
3
2
2
2
2
Leadership
3
5
0
1
1
2
Logistics
3
3
2
2
2
2
Luck
2
1
1
3
1
2
Mysticism
1
1
3
3
3
4
Navigation
3
2
2
4
2
2
Necromancy
0
0
5
0
1
0
Pathfinding
4
3
3
2
2
2
Scouting
4
2
1
1
4
2
Wisdom
1
2
4
4
5
5


Note that only Necromancer and Warlock (rarely) heroes can learn the Necromancy secondary skill. But since undead don't have a morale, Necromancer can't have the Leadership secondary skill. That means, there are only 13 skills to learn for each hero, with the only exception of Warlock who has 14 skills to choose from.