I'm experimenting with a game mechanic that's built around the idea that the core attributes come in Power/Finesse pairs, where the Power stat determines how much you can do while the Finesse stat determines how well you can do it.  a preliminary set of core attributes would be:

[table]
[tr][td]Pair[/td][td]Power[/td][td]Finesse[/td][/tr]
[tr][td]Body[/td][td]Strength[/td][td]Dexterity[/td][/tr]
[tr][td]Mind[/td][td]Focus[/td][td]Intellect[/td][/tr]
[tr][td]Spirit[/td][td]Presence[/td][td]Charisma[/td][/tr]
[tr][td]Mobility[/td][td]Speed[/td][td]Agility[/td][/tr]
[tr][td]Perception[/td][td]Sense[/td][td]Awareness[/td][/tr]
[/table]

[hr]
The basic mechanic is built around two kinds of die rolls: Opposed dice and Aligned dice.  Both use two dice of the same kind; I'm planning on using ten-siders. 

• For the opposed dice, designate one as good and the other as bad; roll both, and toss out the larger one.  If you keep the good die, the result is a bonus; if you keep the bad die, the result is a penalty.  If you get a tie, toss them both out.  This gives you a number between -9 and +9, centering on zero.
• For the aligned dice, either both dice are good or, more rarely, both dice are bad.  This works just like the opposed dice (roll both and toss out the bigger one), except that you still get to keep one when you get a tie.  This gives you a number between 1 and 10, centering just a hair below 4.

The standard task check involves choosing an appropriate attribute pair and assigning a Threshold and a Difficulty.  The Threshold is a measure of how much you need to do to accomplish the task, while the Difficulty is a measure of how tricky the task is. 

1. Compare the Power stat to the Threshold.  If it's at least equal, then it's adequate to the task; note the surplus for possible use in step 3.  If the power stat is inadequate, note the shortfall for use in step 2.
2. Roll Opposed dice and apply the resulting modifier to your Finesse; if your Power stat was inadequate, apply the shortfall as a penalty to your Finesse. 
3. Compare your effective Finesse to the task's Difficulty.  If it's at least equal, you succeed with a margin of success determined by the difference; add any surplus from step 1 to this. 
4. Judge the result based on the margin of success or failure, using the following table as a guide:

[table]
[tr][td]Margin of Success[/td][td]Grade[/td][td]Explanation[/td][/tr]
[tr][td]8 to 10[/td][td]A[/td][td]Extreme Success.[/td][/tr]
[tr][td]5 to 7[/td][td]B[/td][td]Exceptional Success.[/td][/tr]
[tr][td]2 to 4[/td][td]C[/td][td]Standard Success.[/td][/tr]
[tr][td]0 or 1[/td][td]D[/td][td]Marginal Success.[/td][/tr]
[tr][td]negative[/td][td]F[/td][td]Failure.[/td][/tr]
[/table]

Some tasks are pass/fail: if you at least equal the Difficulty, you pass; otherwise, you fail. 

[hr]

There are two variations to the standard roll: the Power check and the Finesse check.  Some tasks are brute force, and finesse doesn't factor in.  To resolve a Power Check, compare your Power to the task's Threshold.  If you have a shortfall, you fail.  Otherwise, you succeed: if the grade matters, look up your surplus on the above table to get the result. 

Conversely, some tasks don't depend on Power.  To resolve a Finesse check, roll Opposed dice and apply the modifier to Finesse before comparing it to the task's Difficulty. 

[hr]

Heroic Reserves
There are two point pools that set larger-than-life characters apart from everyone else: Drive and Karma.  Drive lets you perform Extra Effort (spend a point of Drive to apply the bonus from an Aligned dice roll to a Power stat for the purpose of one task).  Karma lets you replace the Opposed roll in the above system with an Aligned roll. 

Spending multiple points of a Reserve is not cumulative; you choose which roll to use.  Likewise, spending Karma adds a similar bonus to Finesse. 

Thoughts?

Body Mind Spirit Mobility    Perception?
Is there a reason for the "pair terms" or do they only serve as a label?
I ask because I wonder how they are used?
Will they be treated at all like the Power and Finesse attributes?
If so, How?
It might be that their function is one of convenience. Meaning that a GM (if there is one) or player could just say:
"You need to roll against _____ using your Spirit Pair" rather than " roll your Presence and Charisma against ____"
is that their purpose?

I think it cleverly put together but I am trying to understand your idea and just wondering how/if your "attribute pairs" have a mechanical function.
If not maybe you could do away with the Pair term all together. It allows the players to have to remember less or have less to get confused with.
Not that I find it difficult to understand. But maybe they could play a role other than the possible Convenience of not having a mouthful every time there is a conflict.
I am not sure what kind because I don't know anything about your system.

Could you tell us more?

Is there a setting?
What kind of game are you wanting to design the system to be used for?
being that the majority of your attributes are in fact internal (mental) rather than external (physical)
leads me to think that you aren't making a combat heavy game.
What kinds of situations or conflicts do you think your games characters will be getting into or out of?

Good luck to you,
-Brent

In the sample attribute sets given above, the Body/Mind/Spirit/Mobility/Perception terms have about as much importance as Physical/Mental/Social have in White Wolf's Storyteller system: they are strictly organizational tools, with no ratings associated with them.  For the most part, you should be able to resolve a task using one of the defined pairs, although there might be some exceptions (rapidly field-stripping, cleaning, and reassembling a rifle might involve Speed paired with Dexterity, while hand-to-hand fighting probably pairs Strength with Agility). 

The Finesse Attributes (for now: Dexterity, Intellect, Charisma, Agility, and Awareness) are rated on a scale of -10 to +10, with 0 being "typical"; likewise with the Difficulties: +10 is considered to be extremely hard for the typical character, -10 is considered to be extremely easy, and 0 is considered to be challenging. 

The Power Attributes (Strength, Focus, Presence, Speed, and Sense) are probably going to be rated on the same scale; but I've been putting some thought into rating them on a scale of 0 to 10: 0 being absent, 10 being extreme, and 3 being typical.  Whichever way I go, Thresholds will operate on the same scale.  In fact, I'm thinking that the character sheet might need a set of Thresholds on it, for use when someone else's task involves affecting the character in some way: e.g., the Body Threshold would be Toughness; the Spirit Threshold would be Composure, Discipline, Resolve, or Cool; the Perception Threshold might represent natural camouflage; etc.  Alternately, I might switch up the terminology a bit and use Body, Mind, and Spirit as Power Attributes that can be used either proactively (e.g., Body can be used to move or hurt things) or defensively (e.g., Body can also be used to resist being shoved around and/or injured).  It's also been suggested to me that to many people, Intellect and Charisma feel more like Power stat names, and that I might want to go with something like Reason and Expression instead. 

I'm also looking for a sixth pair.  With what I currently have, the pairs themselves have parallels: the Mobility pair (Speed/Agility) shares some conceptual similarities to the Body pair (Strength/Dexterity), forming a pair of pairs that handle most physical activities; and the Perception pair (Sense/Awareness) runs a loose parallel to the Mind pair (Focus/Intellect), leading to a second pair that handles most cognitive activities.  I'd also be interested in a pair that roughly parallels the Spirit pair: for an "urban fantasy" setting that I'm working on, I may go with a Supernatural pair (e.g., Soul/___) or an Ethics pair (Integrity/Wisdom?); though I'm open for other suggestions.  On the one hand, I like the ethics pair because it's more universally applicable: you don't have to be some sort of supernatural adept to justify a rating in it.  OTOH, I'm not sure that I want to assign numbers to the ethical component of characters. 

Either way, those characters who do have access to supernatural powers might need a special pair to represent that - the aforementioned "Soul/___" pair, for which I need some help filling in the blank.  I'm hoping for a "Supernatural Finesse" trait name that works equally well for ascetics, psychics, mystics, prophets, or shamen, the five most prominent kinds of supernaturally empowered humans in the setting I'm thinking of, aqt least to the same extent that "Soul" works as Supernatural Power for each of them.  My fallback position would be to have the name of the Supernatural Finesse depend on which type of supernatural phenomena the character deals with.  Optionally, I may just use the other pairs for this purpose, with the choice of "empowered pair" defining the type: ascetics use Strength/Dexterity or Speed/Agility, depending on whether they're internally focused or externally focused; psychics use Sense/Awareness; mystics use Focus/Intellect; sorcerers use Presence/Charisma; prophets use Integrity/Wisdom, or maybe Faith/Wisdom, although Faith may be a loaded term for general use (I don't want the counterintuitive notion of self-proclaimed skeptics with strong moral fiber having to take a high Faith score to represent it - but maybe Conviction would work?). 

Finally, I'm thinking of introducing Abilities and Skills as traits that give you bonuses to Power and Finesse attributes, respectively.  In effect, they allow you to specialize the attributes so that you can be especially good (or bad) in a more limited set of circumstances.  For example, Dexterity-related skills would include crafts, prestidigitation, and anything else that requires a steady hand and/or fine motor control.  Agility-related skills would cover various athletic activities, Parkour/Free Running, and probably hand-to-hand fighting.  If I go with Body/Dexterity instead of Strength/Dexterity, then Body-related abilities might include Strength, Toughness, Stamina, resistances to various diseases, toxins, and/or drugs, and so on.  Meanwhile, Speed-related abilities would include different modes of movement, improved reflexes, and so on.  Likewise, Intellect-related skills would involve various sciences and academics; Mind-related abilities would include Focus, Memory, and Clarity (the ability to distinguish fact from fiction; used to resist madness-inducing attacks); Awareness-related skills would involve observation and marksmanship; Sense-related abilities would include peripheral vision, night vision, etc.  Charisma-related skills would include persuasion, intimidation, leadership, and so on; and Spirit-related abilities would include Presence, Composure, Resolve, and the like.