Here I try to do a brief summarization of the essential quality of the most successful warriors I have so far observed on the servers. You might feel some lonewolfing here but that's only for convenience of illustration.
1. Calmness
I cannot stress how important calmness is, calmness is one of the most important qualities of a warrior. When one is nervous, he can't sense enemies, he can't aim, and consequently, can't survive.
I think everyone reading this must have the experience of facing 5 enemies at close quaters while alone with a bolt action rifle, it often end up all your shots missed and get killed just because you're too nervous to aim.
Here I should also mention that human eyes are very sensitive to moving objects, sometimes laying completely still is better than trying to run away, nervous players are more likely to get shot while hiding/retreating.
Generally, calmness allows one to use his full potential, thus, they are easily the most deadly ones.
2. Alertness, Sense
Have you the experience of feeling that a particular guy have "superhuman" sense and always found and shot you even when you tries to flank him? Or you always end up stepping on his S mines/tellermines? It could be cheating, but highly unlikely if PB is on.
Normally, a human player can only get information through 2 ways: by sighting, hearing. But one very important quality, intuition, is what distincts the better players from the mediocre ones.
Intuition is, to me, the power of "imaging" the battlefield using limited information.
What could dead silence mean to you? Are there some idiots laying mines in their own base? Or they are all afk and sitting like idiots? While these are possible reasons, it is highly unlikely the case. They are mostly trying to "sneak" behind your lines and shot you from behind.
Very similar for tank combats, when you hear engine sounds while you are not seeing any tanks, they must be all coming from somewhere else other than where you are looking at.
It's obvious, that when you killed someone somewhere, he must be coming for you after the next spawn, first fire a riflegrenade into your suspected hideout, or tries to stab you from behind. Or even call in artillery into your position. Now it's time for sense to work, it can't be a bad idea to place a S mine in some seemingly sweet spot to flank you. Or a drop of the deadly greenbox with good timing could be devastating.
Generally, people would be most nervous at the places that you was hiding, that means they are pretty easy preys if you could guess where they are coming.
3. Guts
I have seen many times people panic in the game, I could comfortably say that, panics mostly don't work in survival.
The most obvious cases are in tanking, say, a Tiger approaching in front, and everyone with Sherman just scared ,sit still and tries to penentrate the frontal armour... or worse, they bailed the tank and got mowed down by MG fire.
In 99% of the cases, the seemingly "wise" decision of bailing often resulted in quick death, as I have many times missed my shots at even empty tanks that I have the bailer mowed down. Or I have my enemy missing their shots even when I am almost sure it'll be a hit.
Guts is especially important in flanking movements or "suicide runs", because the more guts you have you'll be getting in better positions and surprise your enemies more. The most dangerous place is always the place most safe.
Due to time limitations I feel that I should stop here...
