Might as well give a quick run down on the roles and weapons to go for each role:
If you're planning on going as a Tank, I suggest the following weapons:
Dual Wield
2 Handed
Staff
Brawling
I have used all of them and for me, personally, staff and dual wield are very effective. But, I will be honest, for a tank, any weapon is fine to use cos you'll be taking most of the damage from the enemies. While you'll probably spend more time blocking during raids, it helps to have a some serious fighting skills available. For example with my tank, I constantly fight and block only when I need to. Attract the enemies and let your DPS guys do the damage.
For the Healer role, the only weapon you really need is Bow. It's awesome for such a role cos it's a ranged weapon so you can strike from a very good distance. But just be wary if you do get attacked. Being ranged doesn't always mean you are out of harms way as the enemies will find a way to get to you. So always keep moving around and blocking where necessary.
Controller roles are quite tricky but, like Healer, only one weapon is really useful for this role and that's the Hand Blasters. Its use "tap tap hold" of the right click mouse button (no idea what it will be for a game pad/controller) will get your power bar back up in order to restore power to others in your group. One thing to remember about the controller role is that if you go into a raid (group of 8 people in this case), you will have two contollers. The one with the highest vitalization is responsible for giving power over time to the group. The lower vitalization controller does instant power and debuffs when it comes to the bosses. This helps greatly if you have the right strategy during raids.
DPS role is pretty much self explanatory (every role: tank, healer and controller all have DPS as secondary roles). Again, any weapon is useful for DPS. But it's all about how you use it. My dps has martial arts, bow, dual wield and even shield for weapons. So I can switch according to what is required.
I will also quickly mention the 9 power sets available:
For Tank we have Fire, Ice and Earth powers. I've never really used Fire so cannot give much on it but I will say that Ice is my fave as I have tried Earth briefly and found it to be ok, but Ice for me is good.
For Healer we have Nature, Sorcery and Electric. I have only used Nature and Electric. I prefer Nature and might be switching back to it soon. Many people have used Sorcery and have said it is good as well.
For Controller we have Gadgets, Mental and Light. I have used all 3 and found Gadgets to be more effective.
And for DPS, well you can be DPS using any of the power sets. Know where to put the skill points and you will epically excel in your damage points.
One thing I have to say is this: EVERYONE HAS THEIR OWN PREFERENCE. No one power or weapon is better than the other. It's all about how YOU play and how YOU skill your player.
Just cos your tank has around 3800 defense does not mean it is the best tank. It is only the best tank if you know how to block, use your powers at the right time and know the combos of the weapon you are using.
Hope this helps. Enjoy