I'd have to go with the 3E version of Monkey Grip, then. The off-hand weapon could be larger as well, with no increased penalties.
Monkey Grip does not make logical sense, if extrapolated literally. If only your hands and wrists are strengthened, but they are strengthened to that extent, then you will be wrecking the rest of your body very quickly trying to pick up and employ heavy weapons. Or you will be trashed as you are repeatedly thrown off your feet by the torque of a swung weapon (or, thrown off your horse or flying mount, etc.)
Also, if your sword is 7 feet long but the opponent is 1 foot away, hitting him is problematic. Just drawing your weapon is problematic in the first place (you hurl it out, watch it twirl in the air, catch it as it drops by the hilt, and start fighting then?)
I take Monkey Grip with salt.
My extrapolation of Monkey Grip is that it makes you like Tarzan. You gain supernatural strength bodywide, so that you can actually function like ... like a monkey. You could, with some training, branchalate (the feat is needed), or humble an olympic gymnast on the monkey bars (a lot of ranks in gymnastics needed.)
You could attempt branchalation without the feat, and end up splattered against a tree like George of the Jungle. You could attempt gymnastics without training, soar high into the air, and break something (possibly your neck) when you fall and hit the bars wrong.
My version of Monkey Grip grants you the ability to wield larger weapons with the ease and normality with which you'd use weapons for your size category. You must be proficient with those weapons first!
Thus, you can wield a large mace and not be thrown off balance or fall. You can swing a large long sword and not dislocate your shoulder. You can even swing two large long swords, and somehow not constantly run them into the ground, into each other, into the nearest walls, or into your friends.
Likewise, you are somehow able to unsheath the weapon (even if you are 4 feet tall and the weapon is 15 feet long, as mentioned above with the elven girl.) You can (amazing!) somehow strike at an opponent 1 foot away with said 15 foot sword (don't ask me how, because I don't know: you can just do it.)
You don't gain any BAB or damage bonuses (that's what strength and many other feats are for.) You do suffer the -2 penalty. But you can use an oversized weapon in either hand. You could pick up an oversized item and use it as a weapon. You could even pick up a person and use him as a weapon (he would probably have a problem with this.)
You CANNOT pick up and use weapons two sized categories larger. That's for the Epic Feat, which represents a major supernatural ability.
Monkey Grip requires tongue-in-cheek and suspension of belief, and more than a little humor. Otherwise, how do you mentally cope with situations where two 4 foot tall people, each equipped with two 8 foot long swords, are battling each other at 2 feet in a duel of swords, while surrounded on all sides (5 foot hexes) by battling allies, walls, ceilings, and the floor?