Feedback from Garomac

If you don't mind my two cents, I was in a very long-running Amber campaign where we frequently fought people with much higher attributes that had no compunction about killing us.  

The rule we used was that a higher rank beats a lower rank, assuming all other factors are equal. It's that last bit that's important. If you are fighting someone with a higher warfare, you need to cheat. Use your strength, get the high ground, bring several friends, use better weapons, etc., etc. I found that fighting superior opponents really got the creative juices flowing.  

One time we had to fight the most powerful non-Amber/Chaos sorceress in all of shadow, a real Morgan le Fay type whose Psyche was up over 100 and had Exalted Sorcery, a ton of items with points, and thousands of years of experience. On top of that, we needed to take her alive. Had we gone straight at her we would have been toast. We lured her away from her hidden stronghold, to someplace where magic was weak, brought a ton of allies, used every spell, power word to and loose piece of furniture we could lay our hands on, and were able to capture her. Granted, my character got body-slammed by her guardian golem which broke most of the bones in my body, but we pulled it off.  

Another thing to consider is that if you have ranked warfare and fight defensively, it is almost impossible to be one-shot even by a much superior opponent. If Grant runs into Korvalis, he should be able to survive long enough to fall back, pull a dirty trick, call for help, etc.  

I hope that helps.