Armorsmithing is used for creating shields, chain helmets, plate helmets, chain armor, and plate armor. Armorsmithing is very useful to have if you are of the Priest or Warrior classes (aion gold), as you can fill 6 or 7 inventory slots with high quality crafted gear, making a big difference in your characters statistics. Armorsmithing really only requires Aether, ore, and Kinah.
If you are like us and want a full set of the best possible gear, in order to get a proc out of it, you will spend 5 hours gathering hundreds of ore and Aether to craft 5 of one item in Aion. This not only is a huge time sink, but it also becomes very expensive, as turning raw ore into usable ingots is very expensive. And if you do not 'proc', the failed item is barely worth as much as you spent on it.
However, it is very nice to be able to have a full set of great gear every 5 levels (aion kinah). Basically, if you are a Priest or Warrior, we would suggest picking up Armorsmithing, even the basic recipes craft decent gear. As far as using it to make money, it simply requires too much time to be of any real value, but occasionally you will have an extra procd item that will sell for a lot.