I was very pleased when each faction got a unique attack and ability. I think one of the major issues with Elemental is how similiar all of the factions are. Granted, it is difficult to differentiate units when everyone can build the same units. Having different equipment types (chainmail, light plate, Tarth bows, ect) help, but I think a few simple things could be added to make the factions more interesting, while supporting lore and gameplay.
I would like to see unit traits and buildings, unique to each faction, be added to LH. These would be unlocked through the various tech trees at points that make sense for each trait and faction (for example, perhaps Pariden would unlock their traits through the Magic tree, while Gilden unlock many of theirs through the Combat tree).
Here are some examples I came up with that belong to the three factions I am the most familiar with.
Building: Golem Workshop - Golems built in this city gain +1 attack per city level. City gains +1 hammer for every iron resource connected to it.
Mountaineer (+1 movement and sight on mountain terrain), Wealth of the Empire (unit has no upkeep), Strength of the Earth (unit's armour and weapons weight nothing)
Building: Scrying Pool - Provide an additional essence to the city. Increases view outside of the cities border's by one.
Conjurer (all elemental damage is doubled), Studious (-1 attack, +30%xp), Glory of Pariden (all bonuses from elemental shards are doubled)
Building: Ranger's Guild - All outposts connected with the city have their upgrade costs halved. City receives an additional ranged defender.
Ambusher (unit gains an additional first turn in forest, mountain, or swamp tiles), Ranger (unit cannot miss), Survivor (when killed, unit may act one last time)
Even if my suggested changes are not accepted, I still hope the devs will things similar in spirit.