Radagon beat my ass constantly but I'd survive a hit before I was down for the count. hopefully you have at least 40. I am pretty sure The Stars Queen's and our wife's hat doesn't affect Raddy/Eldy as they are completely immune to status effects. I don't think armor does much of anything, but maybe if you respec and throw more into vig you can survive. I use Morgott's Great Rune for the HP buff and my HP bar is absolutely massive.
I like the concept of going full offense but the 1 shot kill is brutality. if you don't have the Halidrake Talisman +2, I promise you that it will prevent a 1 shot kill! go grab it. combine that, and then cast the Lords Protection incantation before you enter the fog and you'll be good to go. its an entirely different fight I promise man.