[Sandman]

Wheeeeee, more suggestions, ripped off from assorted similar games, or just made up by me:

Enchanter, Conjurer, Thaumaturg, etc: Casts the corresponding spell school with improved effect.

Armourer, Offense, Archery, etc: Shamelessly ripped from HOMM3, or Warcraft 3. Leaders with these skills give their units a hefty bonus. This would be a nice way to beef up the mundane units and commanders versus magical stuff.

Chosen: The hero is rendered immune to curse, horror mark and certain afflictions.

Creature Specialist: Creatures of a certain type get a boost when commanded by this commander.

Spell Specialist: Spell X has an improved effect when cast by this commander. This is already in the game for the Vine Men/Ogre spells, and a few others.

Crusader: The hero gains sailing, siege skills, supplies and perma-blessing.

Conquistador: The hero gains sailing, supplies, pillaging and patrolling. And spreads disease among the natives.

Raider: This ability allows ground commanders to initiate an attack from two or more squares away, like flying units.

Weaponsmaster: The commander can replace the weapons wielded by troops under their command with weapons from the province the army is currently occupying. This process costs resources.

Pilgrim: This hero gains increased experience and skills for each temple or holy site visited at least once.

Explorer: As above, but for each previously unentered (by your forces) province.

Wanderer: As above, but instead of stats, this hero gains research skills for each lab visited. Might need to be capped at some point. Same for all the 'traveller' skills.

Scavenger: The ability allows a modest % of gold and gems to be recovered from destroyed units in the aftermath of a battle. Enemy items are very likely to be recovered.

Freelancer: This hero can summon a mercenary camp and freely trade units for gold, gems or other creatures.

Forge Scrying: A unit using this skill can detect any magical items forged anywhere in the world (but not items gained in other ways). At high levels, the forging nation can be determined, rather than guessed at. At divine levels, enemy item stocks can be observed.

Incorruptible Essence: Anyone trying to use lifedrain techniques on this hero will take enormous damage, or, in certain cases, be mind-enslaved to the 'victim'.

Slayer: Grants substantial bonuses when fighting against certain classes of enemy; skeletons, devils, trolls etc.

Guerilla: Allows the hero and/or commanded troops to join the battle from the side or even behind. Some measure of stealthyness should be needed to use this skill.

Partisan: This hero can recruit troops from enemy-held provinces. The troops must be stealthy, of course. Maybe not high-level national stuff.

Terminator: If this assassin manages to kill his target quickly enough, the enemy will not even get to view a battle (and thus be unaware of the assassin's nationality or equipment). They just get a message saying that their unit has vanished without a trace.

Pioneer: This unit can perform the command 'colonise' which greatly boosts the growth rate of under-populated provinces.

Initiative: This commander attacks so quickly that the enemy doesn't have enough time to form up properly. All enemy units are slightly displaced from their intended positions.

Smuggler: Grants sailing, stealth and the ability to steal gold from enemy provinces that are adjacent to yours or one sea province away. It's twice as effective in coastal and river provinces.