Dawnguard Rune Axe is probably the best weapon against the undead.
This question belongs to the spoilers section so, I'll wait till the mods move it there, before contributing
Just dual wield Windshear and Chillrend and you'll have no need for anything else.
You can craft better weapons that what you can find. However, if you're just collecting or lack the crafting skills... they are listed on the http://www.uesp.net/wiki/Skyrim:Unique_Items#Unique_Weapons page from the UESP.
Most of my characters prefer weapons they found at vendors, or (in my Khajiit's case) items they enchanted.
My Imperial: Ebony war axe of Thunderbolts.
My Redguard: Dwarven war axe of Devouring.
My Khajiit: two Elven war axes, Flesh-burner (25 hp fire enchant) and Blood-drinker (13-hp health absorb)
My Dunmer: Looking for a glass mace with a decent health-absorb enchantment (preferably Devouring or heavier)
Finish the quest, the mace gets much better and is one of the better 1 hand weapons imo....couples well with the Black Star
Bolars' Oath Blade, I think.
I like Ghostblade, though probably not a popular choice...
I like the nightingale bladee. It suits my character well
I would tell you, but, alas, we are not in the correct forum for such spoilers.
Just... go exploring Eastmarch, the Velothi Mountain range. Read 'Of Fjori and Holgeir'.