Dual Wielding only works with Light weapons, example: Daggers, Shortswords, Handaxes etc. The Dual Wielder feat available at 4th level allow any weapons usable with one hand be dual wielded. This is also how 5e works, and I have found the game not different.
Actually it states in book that (not word for word, mines upstairs atm, and having hard time walking) That dual wielding can be done with any one handed weapon, (just as in the real world), but you won't be able to use your modifier without certain feats, and you recieve negatives to your normal modifiers, this being more severe and normally starting out as -2 -6 or something. The use of feats such as dual wielding, and 2 weapon fighting allows you to use your modifiers to the damage of your rolls. and make the penalties for fighting with two weapons less. This is further reduced by wielding a light weapon in your off hand, or in each hand. which is why most people go with light weapons.
What your talking about is the feat itself, and the subclass of ranger/fighter.