If you're looking to make money with your profession, you're gonna be disapointed. As more and more people play, you become less and less unique in the items you can craft. When this happens, there will be less demand for those items, which means you'll have to sell them for less than it costs you to make them.
If you're looking to be a good guild player, find out what they have already, and choose something else. Someone already said that it's counterproductive to have two armorsmiths.
If you're looking to make items to benefit yourself, you can only use one weapon at a time, but multiple pieces of armor. But remember, eventually you will transition to end game content and start obtaining gear from the raids you run, replacing everything you have crafted for yourself.
I went with the third option, but i ended up flipping a coin to make that decision.