Heh, oh the glory of open world games. So I've just been running around exploring tons of shit, upgrading as much as I can, following the quest signs when I feel like it. So what happened for me was I ended up killing Fire Giant, and doing all of Crumbling Farum Azula, including killing Beast Clergyman. Then I was like "Hey, I haven't done Caelid yet, let me go there" and suddenly Im basically one shotting everything. Make my way to Radahn. Get in the fight ready for some serious ass pounding but I'm chunking him for like 15% of his HP on every attack. Hah. Beat him on my 3rd attempt. And it only took 3 attempts because I had to figure out how to actually get to him without getting ass pounded.