In my Conan game, I wanted to liven up combat a bit. Instead of just having two characters slug it out (albeit with exciting description) in the normal D&D fashion, I wanted to add heat butts and elbow jabs, and see people people grappling and using their daggers to slice a foe's throat. I wanted them to be able to trip their foe or kick 'em in the chest, knocking them backwards.
I wanted combat to mirror this...
[ame=http://www.youtube.com/watch?v=_b6got4G4Ys]YouTube - Fight scene from the film Centurion 2010.[/ame]
There are rules for all of this in the game, but those rules seem to get used sparingly because, when you use most of them, you allow your foe to first take an Attack of Opportunity on you (for example, if you punch your foe, you make yourself open to an AoO first--and that makes attempting the punch not worth it).
(I'm talking about 3.5 E, here, and specifically, the Conan RPG, not 4E, which I know nothing about.)
What I did was to encourage the type of fighting you see in the youtube link above was this:
First, I adopted the Active Defense rule. You know the one. It's where you roll your defense rather than have your attacker roll against an AC number. Take your AC and subtract 10 (the average roll of a d20 is 10). Then use the remainder as a modifier on your defense roll.
Thus, if you have an AC 17, your defense roll is d20 + 7.
The attacker rolls his attack normally, then, in opposed roll fashion, the defender rolls his defense.
The next thing I did was throw in some exciting variables that can happen during a fight.
Natural 20 throws...
If the attacker rolls a natural 20, it's a critical threat, per the normal rules. Roll to see if the hit supports Critical Damage.
If a natural 20 is rolled on the defense roll, then the defender just parried or dodged in such a way that he's gained a counter attack on his enemy. This counter attack is a free action, but it also counts and an Attack of Opportunity (and characters are usually limited to one AoO per round).
Natural 1 throws...
If the attacker throws a natural 1, or if the defender throws a natural 1, then he has opened himself up to a special limited attack of opportunity from his foe.
This special AoO is limited in that it cannot be a lethal attack. It must be an attack aimed at delivering nonlethal damage or some other nonlethal type action.
Thus, if your foe throws a natural 1, you have an opportunity to heat butt him, punch him in the face, elbow him, knee him, kick him in the gut.
Normally, a foe would earn an AoO against use for such an action, but under this special rule, when the natural 1 shows on the attack or defense roll, the target's AoO is ignored, making these types of nonlethal attacks safe to use.
So, when your foe throws a natural 1, you may attempt an unarmed strike safely, but you might also want to start a grapple, sunder his weapon or shield, attempt to trip him, among other options. All of this is legal as long as the character doesn't move or attempt to deliver lethal damage. He may use the Bull's Charge, for example, never leaving his square but using his leg to kick his foe in the gut and knock him backwards.
When Attack = Defense....
If the attack throw ties the defence throw, different things can happen. In the Conan game, a player can either Parry or Dodge (using different modifiers) when defending himself. In the standard D&D game, one could just pick or figure some system for determining which of the below to use.
If the attack throw ties the Parry defense roll, and the number is even, then the two weapons are locked together (and there's rules for this--an opposed STR check). If the tie number is odd, then the attacker gets a free sunder attempt on his foe's weapon. Again, the defender does not get an Attack of Op as he normally would if someone tried to sunder his weapon or shield.
If the attack throw ties the Dodge defense roll, and the number is even, then the attacker is allowed to take a free 5' step to better position himself against the attacker (or even to get out of threat range and leave combat on his next turn).
If the attack throw ties the Dodge defense roll, and the number is odd, then the attacker gets a free Trip attemp against the defender. Again, normally a defender would get an AoO against someone trying to trip him, but in this situation, the defender's AoO is barred. It's a consequence of the tie.
I find that these rules are perfect to making my Conan combat look like what you see in the video. Many, many strikes are just normal blows, but if a natural 20, natural 1, or a tie shows up, something interesting is going to happen that may change the nature of the combat.
