Thought I'd mention that Intensify, while very good at producing hilariously oversized opponents, is actually a skill that cranks up the values on any buffs both you and your opponent have. Thus, if you give yourself a buff right at the start of the fight (might I suggest putting ranks into the Jumpstart skill in the bust tree, it's very useful), then even if you encounter an opponent who spams intensify, they're basically doing you a favor.
I will admit that armor, proper block-providing armor that isn't either the weighted set or the leather leggings, is hard to use after you level any respectable amount. But that's kind of the point, I think: you start out super squishy and thus need all the help you can get with just surviving fights, which armor does for you. But once you get bigger, you rely much more on buffs and modifiers than armor to win fights, since 30 extra block from a maxed-out armor piece can be removed rather quickly by... well, most opponents honestly.
Lastly, yea starting a fight while there's a second potential opponent right next to the person you're fighting can break things pretty easy. I once had an issue where I got put into a second fight immediately after exiting the first one, and upon winning that one, was unable to walk, move the camera, interact with anything, or do anything at all besides open the menu to quit the game. Not any of the levelling or inventory menus, just the one that pops up when you hit escape. Watch out for that.