Best warhammers you'll find at level 2 are silver and amber. As mentioned, one (silver) can be found by a drunk, dead goblin in Toadstool Hallow cave along the road south of Bruma and another can be found on a bloody table in the back of Castle Leyawiin's secret torture chamber. If you have Shivering Isles, try to find some amber and bring it to the orc smith in Bliss (New Sheoth). It'll be leveled, but he can make you an amber warhammer. IMO though it doesn't look overly "badass" http://images.uesp.net//d/df/Amberweapons.jpg Absolute best one in the game though, IMO, http://images.uesp.net//9/9c/Nerveshatter.png found in the Shivering Isles. Best when you're at level 30.
There are two unbelievably sweet war hammers in the Shivering Isles. I tell you man, sweet. They will be the best quality at level 30, iirc. Both are found during the main quest there. One guaranteed for sure, the other, when you enter a particular room, the game checks whether your blade or blunt skill is higher, and the weapon you receive will be either a hammer or a claymore.
Really? Mine always turn into a battle axe or claymore. I've never had it be warhammer.