So going through a bunch of different playthroughs, I have noticed a continuous theme when deciding to outfit my sovereign, champions, or henchmen with a weapon. That theme is no matter what fancy weapons I picked up from loot or quests, or what weapons I have available to buy/create through researched tech, that the Lightning Hammer will outshine 95% of the weapons (lol Curgen's Maul and Scythe of the Void). The Lightning Hammer is a weapon that you can not only find at a reasonable rate through loot on maps, but you can research in the magic tab very early as it is in only the 2nd tier of techs with one prerequisite.
It's stats are:
9 blunt damage
+1 lightning damage per level
Bash -Has a chance equal to the damage done of knocking the victim prone.
One handed, weight 15.
It's a warhammer with the +1 lightning damage per level bonus added on. That bonus is what makes the weapon too powerful in my opinion. Compare that to even the more powerful weapons that you have found or the weapons you can research in either warfare or the magic trees. The tech that allows you to create a Lightning Hammer can be researched after a total 55 units worth of research from the start of the magic tree, but the next set of weapon tech, Magical Forging, is all the way at 422 turns from start assuming 1 research unit per turn and beelining it there. The next and highest tier of magic weapons, Arcane Weapons, is at another 418 units of research after Magical Forging.
From those last two magic weapon techs, the Burning Battle Axe, Boreal Blade, and Lightning Pike are weapons with a flat +6, +5, and +6 magic damage enchantment. The Lightning Pike is actually 3 less base pierce damage with a +50% lightning resist compared to a normal pike and the Burning Battle axe only has 12 base cutting damage which I think is low for a 2-handed weapon. They all cost 5 crystal too while the Lightning Hammer takes 2. By the time you can get that far in the tree the Lightning Hammer can be doing double, triple, or more damage easily because of the scaling damage.
It doesn't take a lot of time for sovereign, champion, or henchman (power-leveling + this hammer = OP) to get to a level where the Lightning Hammer will be superior to anything you can make or find in terms of damage, and soon you don't even need to take more than a second to just sell off whatever weapon you find. For casters I usually prefer to hang back with a nice dagger or the fastest weapon I can find, but for anything smacking stuff, the damage gets ridiculous. The blunt damage has its pros and cons against stuff, with an advantage against many mobs but lacking vs plate armor. What really shines is the lightning damage per level, which will just eat up almost anything it hits. I have found fire and ice to be the common magic types that units will either resist or be weak against, but lightning is rare either way. Magic damage of any kind is powerful though, which is why I find myself using the ice/fire staves a lot (maybe OP too compared to bows, but that is another topic).
I feel that something should definitely be changed with this weapon. Maybe the lightning enchantment on it should be modified to be a flat amount, or less damage per level. Maybe you could take that same enchantment and throw it on a different weapon, like a bigger hammer later in the tech tree. Either way, I think that some changes need to be made with this. One of the aspects of the game I find enjoying is seeing what loot I get, and equipping my guys with cool stuff. To get something so early that trumps almost everything I later find doesn't seem right.