I think of Monkey Grip as a quasi-magical feat of sorts: Call it a Supernatural Ability obtained through a feat.
A 4 foot tall elven woman is a medium sized being.
A medium sized long sword is, what, 3 to 4 feet long, in total length?
Within the regular rules, that elven girl can wield that 4 foot long sword, which is as long as she is. She, obviously, has very strong wrists!
Indeed, she can wield a 6 foot claymore if she holds it in both hands, since a 6 foot claymore (two-handed sword) is also a medium sized weapon.
Now, give her Monkey Grip.
Our 4 foot tall elven girl can now wield, in one hand, a weapon intended for a Large Sized being ... meaning a being that stands 7 to 10 feet high, right?
Thus, our 4 foot tall elven girl can now wield, in one hand, a long sword that is up to 10 feet long.
She could wield a claymore that was 15 feet long (using ratio and proportion: 6 to 4, 15 to 10) using both hands.
Needless to say, weapons of this size are extremely heavy, produce great torque on the wielder, and simply unsheathing them is an interesting exercise all in itself. But these are not problems for our elven girl.
Our elven girl can freely and easily do (wielding a 10 foot long sword in one hand) what no human being in the real world could ever do.
Obviously, then, this is a Supernatural Ability! (but, it is not suppressed by things that suppress Supernatural Abilities.)
I think this is a neat feat, personally. It enhances the fighter, and she needs enhancement against all those spell-casters out there.
And, the look of astonishment on the face of the big, bad ogre when the cute little elven girl draws out two 10 foot long swords and begins wielding them both simultaneously, is priceless.
Edena_of_Neith