Coup de force.

I used to think that when the first force-feedback joystick was put on shelves, it would be the perfect controller for a lightsaber. And it would be just perfect for Dark Forces2: Jedi Knight. Which, admittidly, I played with a Joystick. At the time I felt there was similarity between holding a lightsaber and holding a joystick.
Only later did I adopt the mouse. You must understand, I was a huge Flightsim buff before that. Either way, that game was awesome. Even with my rather unusual control style.
But I was wrong. About 10 years later the Wii came into being, and along it the Wiimote. It has been said over and over. The Wiimote would make for a perfect lightsaber. At last all the pieces were poised to fall into place. But I was wrong again. At least for now. Let's make amends.

Let us use our most remarkable human gift of reason to try and solve this problem.
Here goes.

We all remember Lucasarts much maligned Star Wars: The force unleashed and The Clone Wars: Lightsaber duels, yes? They are lacking, to say the least.
Krome Studios made both said games in respective order.
Logic would have you think that the second go would be a better one then the first, right? Wrong.

What I think happend is, Lucasarts dropped the ball. Into a toilet. Then accidentally flushed it. On the long way down it got shittier and shittier. Eventually an aligator ate it. The aligator commended himself on being able to digest anything, very slowly.
Since then, Lucasarts and it's variable minions have prodded the austere aligator for a long time in hopes it would regurgitate the ball. Often the reptile would crap into the wet sand behind it and the minions would scoop up the seeping waste, mistaking it for the much coveted ball. Then they release it in gamestores everywhere.

So Listen up Lucasarts and Krome.

A bit of free time and a sugared up coffee has produced this little brainstorm session.

The lightsaber combat game works like Metroid Prime 3, "lock-on" viewpoints with 1 on 1 movement (Wii motion plus included if it helps).
Locking on sets the player in "guard/fight mode" allowing for combat moves. The lock keeps the opponent dead center in view, this eleminates the need to manually adjust your character's direction, or the camera's, on the opponent. I honestly can't imagine a viewpoint in a duel where you'd want to have your opponent somewhere in the corners of your eyes while fighting.
Locking off makes the player more mobile. This so he can better move around and reposition, jumping on platforms, running away, etc. If Third person, this also makes the camera zoom out a bit.

Further controls.
A pointer or Crosshair controls the camera and look direction - pitch and heading when not locked on. Not locking on puts the saber and the sword arm in an idle state. That way you don't have arms waving every which way when controlling the camera.
Strafing and forward and backward movement are controlled with the analog stick. Lock on button is mapped to the Nunchuck's Z button. You don't want to press and hold a button on the controller you're waving about.

The game might not be able to know just where your hand is, nor where your arm is.
The wiimote and the wii are not equipped to gauge the absolute position of the wiimote in space. The player will have to adjust his movements to the "hand position" shown on screen. This opens the door for additional gameplay, we might be able to set the hand of the character on screen via combat styles. A bit like the combat stances in Jedi Knight 2. For instance a more defensive position has the saber placed in front of the viewpoint, allowing for easier blocking. The trade-off here is that the player is unable to make huge swings, making for weaker attacks. Reverse the previous situation and we have an agressive combat style.

First person view might work for this concept but third might be better.
Perhaps a view not too far out as not to be disconnected from the battle. Something of a closer view Jedi Knight 2 had. Over the shoulder might work too, but only if overview remains.
The reason third person works well is that it's {the "narrative of the combat"} focussing on the characters, their "bodies". As opposed to the first person view that makes the body something of an afterthought.
Third person gives a player more awareness of their environment right away. Mirrors Edge made a solution but it didn't incorporate combat all that much. For instance Metroid Prime had people jumping out of good faith, rather then exact knowledge. And it became something of an instinct. But again, MP has no melee combat.
In a lightsaber fight though, it might be necessary because of acrobatics, force jumps, etc.
Maybe this is one of the reasons Jedi Knight played so well in third person view, limited though it might have been. In it Gunplay didn't work well because it lacked a more zoomed in view, like the "over the shoulder" viewpoint we see so much and works so well.

In multiplayer though, I can see why a conservative studio might want to place the fighting on a 2D plane. But in order to coordinate exact movement, it's best to have the camera squarely behind the character.
So might I suggest a split screen? Preferably a vertical split.
Online play is a must. No more excuses.

Setting.
Personally I'd rather see the game in a timeframe where there's more then just a handfull of hero characters. Which brings about my next point.

High customization.
Players choose their race, gender, clothing combinations (robes or armor - mobility, defensive trade-offs?).
player gets to create a lightsaber, customise it's properties, choose the colour of the blade. To keep it fair, offer the "canon" colours in different shades.
Add chrystals and mods. More power - less defense. More speed, less damage. The usual.
Unlocks might be considered, though not along the lines of "unlock a more powerful version of this modification" rather "unlock a different kind of modification".

Force powers are there, but limited. Force push sounds like a given. If you must include more then that, stick to force choke, lighting and healing. Also, blinding as a light side power could be cool. Force power could be stored and accumulated like the power meter in the Street Fighter series. On a side note: super moves on a full powerbar could be cool, if they are not overpowered. This would be a good risk-reward move. Or when the fight starts to favor one player it might even the odds a bit.
Jumping and running could be a possibility, but have a stamina limitation, this to prevent people from endlessly running and jumping around. Keep the game about the duel!

Hurdles to overcome.
-Multiplayer lag.
-Possibilties for Local multiplay. (split screen?)
-Noobs slashing their way to victory (link stamina meter?).
-Huge expectations could jeapordise the gameplay, the game doesn't have to make you Darth Maul to make it fun.
-Graphics on Wii are a problem for some. As always choose style over technique. Cartoony graphics with a very limited polygon budget will work best. Have background that are functional first, and look pretty second - like making them in grey or earthy tones. A lot can be done with very rudimentairy geometry and simple textures. That way the combatants and their coloured lightsabers stand out more. Silhouettes are important, stance of the feet, positions of the arms tells the player their combat style, etc.
Photorealism is so far out of the Wii's reach, don't even think about getting there. Think World Of Warcraft rather than Doom 3.
-If there are no canned animations to count on, putting the movement of the player into animation might give a huge disconnect between the movement of the saber and th that of the character. Which in turn might favor a first person viewpoint.

Under- or overambitious? You might have similar ideas. Feel free to sound off.

Additional References:
Wii Controller for Virtual Reality