I discovered that as of 4.0 barrels and hilts for player modifiable weapons are now artifact authorization required. I have not found any barrels or hilts for any level/tier of weapon from a merchant/vendor that is "normal" and not requiring AA. Armorings, Mods, and Enhancements don't require AA as far as I saw, but barrels and hilts DO. I have seen crafter made barrels and hilts on the GTN being sold by players but price is 20K and over. I won't pay that much as a low level character and I don't have high levels to cover the costs. I was a subscriber in the past, I have bought CCs in the past, but never needed to get AA because there just wasn't that much of it in the game that I ever saw. Barrels and Hilts determine DPS of modifiable (orange) weapons and if a player can't purchase from a vendor barrels or hilts without AA requirements or without crafting, then a character won't get very far in the game.
I should also note that I have failed to find the location of a weapons vendor that sells non-modifiable weapons, so even that option is gone (or moved and I haven't found it yet).