I want to be afraid of dying in combat. Not every time of course. If i'm a skilled warrior and some street punk tries to mug me then dispensing of him should be no large task, but when going up against skilled fighters, ancient horrors, mountain giants and the fricken King of Worms, I want to be unsure if I will make it out alive or not. I want the battle to be epic, yet desperate at times. I want to use my actual skills as a fighter to go blow to blow with my enemy in a struggle over who will walk away. I want a fight against someone to last for more than a few seconds.
One of the first thing's I noticed when I played Fallout: New Vegas for the first time was the fear of death. Wondering around dangerous areas and fighting fearsome opponents felt frightening and fun. Sometimes I didn't know if I would make it or I would win but just barely, limping away, unsure if some new threat would come out of the wilderness and finish me off.