As I stated earlier, the basics of Renaissance fencing and martial arts (the discipline we call "MARE," or Martial Arts of Renaissance Europe) are pretty straightforward, and once you understand them, the rest becomes a matter of relentless conditioning and practice.
For the purpose of the animator, however, the basics can be a great starting point that will give your warriors a unique visual silhouette, without requiring the animator herself to become a scion of martial prowess.
Once you're comfortable with holding the sword, the best place to start thinking about animating a swordsman is to understand the basic stances: what we call "tip progressions" or "guards."
For the purpose of our animation, it's best to think of these stances as our idle positions.
As you begin to employ these idles, you'll notice that no matter what sequence of cuts your characters perform or what direction they face, they will always end their movement in one of these poses. They work fluidly and efficiently with each other, and they emphasize control and tactical positioning.
The four primary guards, as illustrated by John in Figure 2, are (from top to bottom) Phlug, Alber, Vom Tach, and Ochs.
Figure 2: The four primary guards: Phlug, Alber, Vom Tach, and Ochs.
What you'll also notice is that they play very well with your inverse kinematics rig. Like the algorithms that drive your rig, the weapon leads the motions, just like your IK target leads your animation. You'll also notice that the torso and arms seem to move almost independently of the legs. What's more, as you step through the footwork, you'll find that you can pivot your character around on a single foot, and stepping forward or backward is a simple matter of just mirroring your animation across your center plane.
Of course, these idles require the context of the basic cuts (called "Master Cuts") to be fully appreciated. Rather than go through the entire catalogue of idles, transitions, and cuts, I'd like to illustrate my point with a particular sequence.
In Figure 3, I start at the top in a fifth guard, called Nebenhut. Note how my leading leg is bent, and the trailing leg is straight. Also note how my feet are at a 45-degree angle to each other. Let's pretend that a new enemy has presented itself to my rear, and I want to turn 180 degrees to meet the new threat. Rather than shuffle around and swing my blade awkwardly in an attempt to maintain Nebenhut, I opt instead to hold the sword steady.
Figure 3: Example of turning 180 degrees between two guard positions.
As I begin to turn, my head and torso rotate first, followed by my trailing foot, which ends at 120 degrees (as relates to my left foot). On the third step to this sequence, I shift my weight onto my right leg, which is now my leading leg, and I deliberately bring my trailing foot to its new position. Notice that now our Nebenhut has transformed into Alber. To end the sequence, I lift my weapon out of Alber, and into Phlug.
Despite turning my entire body to face a new direction, my right wrist (the presumed target of our IK), never changed position. Also, until I lifted the weapon at the end, the sword remained almost entirely motionless. Note that for my entire turn, the ball of one foot remained planted in a single position (please ignore the general position shift at step three; a wall was in the way, so I had to move back).
This theme of always returning to our basic guards continues to manifest even as we begin striking. In Figure 4, we see John start in a Vom Tag, and then step forward into a strike. What follows is a rapid rotation of the weapon to strike again from the opposite angle. He repeats this rapid back-and-forth several times, striking at a different angle on each pass.
Figure 4: A sequence of strikes starting in Vom Tag.
Despite the change in vector for every strike, John always returns to Vom Tag before striking again. He doesn't do this because he's necessarily trained himself to perform this specific transition for its own sake; he does it because it's the most biomechanically efficient way to pass from one strike to the next. This phenomenon is particularly useful for animators, because at any point between strikes we can end our sequence without popping into an idle pose, potentially jarring players out of their immersion.
Exaggeration is, fundamentally, one of our jobs as animators; we make our characters perform like an actor would perform on stage or on camera. Reality is always exaggerated or altered to fit the needs of a production. But whether you're talking about Jade Empire or Call of Duty, you should always start with a solid foundation in reality. For games in medieval or fantasy settings that include sword combat, taking inspiration from the right sources (like MARE) can set your combat animation apart and make the task of animating cleaner and easier.