The answer would be no. It's not just a matter of weight, it's a matter of balance, control and leverage. In terms of balance, a two-handed weapon isn't balanced right for single handed use, the longer handle provides leverage, and control.
In terms of control, a swords balance point lends itself to that control. A thrust oriented sword tends to like the balance point towards the hand, while a cut oriented sword tends to like the balance point forward. Most 2-handers are very cut oriented, and have their balance points fairly far forward (10-15 pounds in many historical blades), making them more difficult to control single handed.
In terms of balance, there is not only the balance of the weapon, but your own as well. Swinging heavy weapons around exerts force on the wielder too. This is something many people forget. Swinging 10-15 pounds of steel around forces you to use big arcing movements and work to control the swing so you don't end up in the dirt, or dislocating a shoulder.
Leverage makes everything easier. Leverage multiplies my strength. It multiplies my control. Leverage with a 15 pound of steel in your hands is crucial.
The same ideas and concepts work with shooty weapons as well. Since the weight is (in most cases) going to be forward of the shooty hand, you need not only overall strength, but strength specifically in your arms, not just in your whole body.
Weapons with recoil will be balanced in such a way as to make use of the leverage between hands to control that recoil. Recoil makes the length of the weapon act as a lever against you, decreasing your control.
In general, two handed weapons aren't two handed only because of weight, but also where and how that weight is distributed. Pick up an iron bar thats about 10-15 pounds and hold it at various points along it's length, both as a sword and as a ranged weapon. You'll quickly see it's not overall strength, but arm strength, and in some cases fore-arm strength in particular that make these weapons two-handers.