"Wielding" is one of those wonderful terms used in several different ways in the rules. There isn't an official definition of it. When you speak of weapons SKR opinion and the defending weapon FAQ say that it mean actively use. Other abilities and writers use it for held in hand/have it ready for use.
As Calth say, you can wield several different weapons and you can possibly use all of them if you have enough attacks or for AoO if you have combat reflex and enough dexterity.
"You can fight with a weapon wielded in each of your hands. You can make one extra attack each round with the secondary weapon."
"Members of this race possess three arms. A member of this race can wield multiple weapons, but only one hand is its primary hand, and all others are off hands."
The missing text allowing you to make extra attacks can mean:
1) that the writer was taking that for granted and wanted to keep the word count down;
2) that the writer didn't wanted to give extra attacks with that ability, but only the ability to held multiple different weapons in the different hands.
That can be a interesting ability, as an example, for a creature using a reach weapon in 2 hands and 2 different non reach weapons in the second set of hands.
Without Dev input we can guess what is the intent, but the multiple uses of wield in the rules don't give us a definitive answer.