forzen

It could also be because you have taken the blessing of the Anchorash Stone (spelling is wrong), it's bugged and makes you fail summoning 50% of the time.

Yes, I do that all the time. I once went into a way to high level crypt, I was about level 20-25 and even the normal dudes two-shoted me, if they wasn't using a two-handed weapon because then I was dead. There were two bosses, one Deathlord with a bow and one without. The one with a bow was impossible, so after 4 deaths I just sneaked past him instead. The other one took three 30x damage dual power sneak attacks to kill, but at last he was dead. First I sneaked his body guards, then him casting Pacify between every sneak. The tricky part was that he was sitting in a throne, so I couldnt sneak him while he was there, so I had to lure him with my bow, cast Pacify and sneak him on his way back.

I'm playing a sneak/illusion character too, on master, and I have felt like I was super powerful all the time. I got perks in Illusion (everything except making stuff cheaper), Sneak (only right tree), One-Handed (only for 50% power attack damage while dual weilding), Alchemy and Pickpocket. Before I got 15x dagger damage I usually just sneaked around and cast frenzy on all opponents until there was only one left, and then did the 3x sneak attack with a sword and calmed him if I didn't think I would be able to kill him. When I got 15x dagger damage I just snuck up and killed everyone dual weilding of course. With calm spells you can always try again if you fail. I leveled really fast until I had maxed both sneak and Illusion, the first 30 levels took about 10 hours maybe, the last 3 levels took the same time. I onehit everything except bosses, and I'm working my way toward the Poisoned perk so that I can just pickpocket poisons into their pockets and watch them die.