I agree that the progression system in the mistlands feels off. You struggle a lot basically with your plains gear until you find enough black cores. Then the upgrade to your normal Armor isn't really an upgrade while they put you up against 2 star seeker soldiers in the mines where you can't even hit their back with a bow. The cape and the magic items are actually good and help a lot but for me it seems like it's a dedicated fighting build because you sacrifice so much health and stamina so farming black marble or other stuff would take forever. It also definitely doesn't help that we get magic so late in the game. As many others here, I built an arena in the swamps around 2 draugr spawners and leveled my blood magic by spamming the shield on 2 skellies until I reached around level 40. I did the same with the frost staff and a trapped stone golem. Then magic starts to be quite good but you shouldn't have to do this just to be able to use a new mechanic, imho.