How does MainGauche and TwoWeapons skill fit with each other?

[Nils_Lindeberg]

I also assume double penalties for lacking talent (knife) and do a secondary attack with the left hand.

So the whole thing comes down to the fact that you can do a left-handed attack (with the knife talent) at -4. Or you could use a shield. And those are the reasons why people wouldn't often use a left-handed fist attack. You usually have something in that hand, and if nothing else, a torch.

With the two-weapon talent you can whack them with any weapon at a -4, so can you do it with a fist attack? Does the fist attack qualify as a weapon in the context of the 2-w talent? Or do you need some sort of improvised weapon, knuckle duster or some such? Could you use a right cestus for your main attack and then with the 2-W. talent attack at 0/4 instead of -3/-3?

The rules are not really clear or logical/intuitive on this.