Buy peices from certain merchants, such as the heavy armor merchant in the imperial city market district in the shop called The Best Defense. When you are a higher level(around 15 or 20, i think), marauders should start wearing it. Go kill marauders until you get all the peices. Dwarven armor is very easy to find, although it isn't that great for defense and looks stupid.
Thieves Guild missions.
if you are looking for dwarven armor there is a mission in the biggining of the game where you travel to fort sundercliff and the bandits should drop dwarven armor. i think you have to download fort sundercliff but dont worry its free
Sorry, but I don't think stores sell armor like that. But you can find it in many places on a level of 15+.
daedric,elven,dwarven,mythril,orcish,glass,ebony,iron,leather,steel,legion,and chainmail
when you are level 7 to 10 go to the Roxy inn..... there will bea lady with full gold on(that's dwarven)so there should be an imperial legion soldier there so wait till he gets out( aroung 12:00); after tht attack the lady with gold once then run out...the imperial will run in and see whats happened...the lady will come after you and the rest willl attack the guards...
As you level up you will find that rare armor starts to appear in the game on bandits and other humanoids The higher your level, the more you will start to find and the more it appears. First is dwarven, next is elven, and so on. I will advise you to aim for better armor though, such as dadric armor or glass armor.
the best defence when you are higher than level 10
basically on bandits in ayleid ruins or in bandit camps. If you need to find anything go to Oblivion Wiki or Elder Scrolls wiki.
once u start get higher in level bandits and random bad guys will start wearing it
You have to download a mod, there is no halo armor in the game itself.
daedric
You can, if you use a mod.