These smiths would need multiple assistants. A single apprentice wouldn't be enough to blow the bellows of the forge for both of them. Maybe the "apprentice" is a junior smith skilled enough to make everyday items like axeheads or knives and leave the more difficult stuff to the two masters?
There's only one apprentice. He's a 14 year old (atm) 3rd level PC. (That level might seem high for a 14 year old, but I'm about to advance the timeline a few years. Plus, the PC is a bit of a hero among the clan, given the events of our first storyline.)
I've described the forge work area as smaller than what I posted in the OP--the pics from the Conan movie. I've established in the game that it is hard for more than two people to work in the forge--too tight of quarters. Two smiths, or a smith and an assistant, is about all that will fit in there and not get in each others' way.
When the PC isn't out hunting or doing something else, they put him to work gathering or chopping wood for the furnance, running errands, making deliveries.
As far as his skill--the character has been around that forge since he could walk. Mechanics-wise, he's got his weaponsmithing skill maxed out. So, yeah, he's a smith in his own right even though his father and uncle treat him as the apprentice.
In fact, I'm using that in the game as a "push" on the character. Sure, the Chieftain has other duties sometimes besides working at the forge all day. When that happens, the PC acts as apprentice to his uncle. But, the PC is learning that there is not a lot of time left for him to be the master of the forge--thus, its hard for him to find time to make his own stuff (not to mention that ore and ingots are prized more highly than most things among the Cimmerians).
This leads to the PC...adventuring. Which is what the game is all about, right?
The size of the forge, the man-power available and able to put to use at any one time, are other reasons I'm erring on the output of the forge being small--but constant enough for these two men and the boy.
Oh, and if they are making coats of mail for the warriors and to trade they'll need a lot more people - it's a very labour intensive process riveting all those links together.
No armor. They make occasional basic shields, and they may attempt a basic helm. But, that's about it. They're, specifically, weaponsmiths--not armorsmiths--in game terms.
Cimmerians tend to shun armor. It's for sissies, like the Aesir and Vanir.