Armorer?

I was just asked if I want to become an armorer

Is that whats called a "job" in this game? If I join armorer guild will I still be able to join other guilds? because otherwise it doesnt make sense to me as an arcanist to become an armorer, or does it?

Armorer is a crafting class. It lets you craft heavy armor for gladiator and marauder. It is ideal if you are intending to make a tank.

You can obtain all classes and jobs in the game without any restriction. Taking any class or job will not affect your ability to join other 'guilds' or pursue other jobs. To switch classes, simply equip the appropriate weapon/tool for it.

so you are saying basically I might as well do the quests for all the guilds so that I can be any crafting class I want?

Yes, if that kind of versatility interests you. Every class except your highest leveled one (main class) will gain a 50% xp bonus so the game encourages you to branch out. It's up to you how you want to approach it, although most only invest in 2 or 3 classes from the beginning and fill the rest out later.

I would be careful about your armory and inventory space as it can be somewhat limited. You'll most likely to run in to that problem at higher levels when you get class- or job-specific armor though. Weapons are not often an issue unless you're saving your old ones.

As said above - inventory space will become an issue soon and even if you'll employ two available retainers you might eventually run out of space if you're hoarding type like me. As the game will not allow you to (directly) pass items on your own other characters on the same server to use them as mules (unles you're multiboxing) the only other "storage" option would be to establish your own FC mainly for the purpose of storring excessive amount of items and gathered or crafted materials.