The op seems spot on with his weights. I've been to the museums to see the real weapons, and their weights agree with what he posted.
People think weight equals power or something. Here's a clue: speed kills. F=ma and all that.
And I do recall at some point the weight was called pounds in TES, just don't remember where.
Daggerfall measured weight in kg.
2 and a half pounds, seriously? thats a joke, the handle alone on a medieval warhammer would be around 4 to 5 pounds, the head would probably be around 10 pounds to be effective. 2.5 pounds? I dont think so.
You don't think so because you have no idea what a medieval warhammer looks like.
It actually depends on the type of war-hammer. A war-hammer is a particular style of weapon, but just like swords come in varying lengths and sizes, so to war-hammers. If you were a mounted unit, you would probably have a shorter lighter one-handed war-hammer for attacking from horseback, and that would be in the 4-5 pound range.
That is a false assumption. Everything on horseback was heavier than normal, because people on horseback were less affected by normal combat fatigue. They could use heavier things because they didn't usually have to carry the weight. I think everyone knows that a real warhammer was almost always in infantry weapon.