This is a bit of an odd wish, and I don't know of a way to impliment it. It just occurred to me and it seems like a good idea. Then again, all of my ideas are good!
There should be times when a fight ends in both parties dying. This should be especially true if both parties are well trained but near equal. If you have two fighters who aren't very skilled, they might be a danger to themselves (hey, there's another wish list item!), but the outcome of the battle could be decided through luck and it could have a clear winner. When you have two fighters who are very advanced though or very powerful, and they're near equal in skill, there should be a chance that no one wins and everyone dies.
Think of that famous photo of a constrictor versus a crocodile. Both died, but the snake half-swallowed the crocodile and then the croc killed the snake from the inside.
In human terms, think Sherlock Holmes versus Moriarty. (Yes, Holmes was later brought back to life, but that only happened because of a massive lettering campaign - the intention was for Holmes to die and really be dead.)
So what do you say? Good idea, or great idea?