Secondary Weapon + Gem questions...

Hello. I noticed that I was able to equip a Dagger for secondary weapon (my main weapon is a Staff). With that said, here is few questions about Secondary Weapon:

1.) What is the purpose of secondary Weapon?
2.) Is there a ideal weapon to use as secondary weapon... as a Mage (are there any secondary weapons that a Mage class cannot utilize)?
3.) How do you use the secondary Weapon? And when do they become useful?
4.) If I want to use the seco dart weapon, do I need to add the Dagger icon into a shortcut button or within the List? Or do secondary weapons get used automatically?

Lastly, I noticed that I have these "Boss" and "Travelers" Gem (30 gems per stack). The Boss Gems are stated as being used during Boss fights. But how do I use them? Do I need to click on the gem for mana gain during Boss fights? Or do these Boss Gems belong on weapons and gears as add on slot item? I am mostly curious on how to use these gems.

 

1. Secondary weapons allows you to use extra skills from different particular skill trees (dagger = dagger skill tree , arrow = shot skill tree , shield = shield skill tree)which you can use as filler skills for your combos. You also benefit additional stats provided by them although it is quite minimal.
2. It ia subjective entirely depending on what role you wanna do in a pt , if you wanna be quite bulky and provide some support then you might wanna use shield but if you want to dps only then use arrow or dagger as secondary weapon.
3. Read 1 & 2.
4. No you don't.

When you click on a boss , before you press ready , there's a button there that will allow you to use which gems you want to use for the fight.

 

they give you additional stats and/or allow you to use certain restricted skills and/ or give a bonus effect to certain skills.

you cannot use Magic Devices as secondary, because you cannot gain their skill bonus if your weapon is a Staff.
but they still lower your atk

as soon as you equip it, the stats take effect, except for MDs and Knuckles.
MDs and Knuckles become useful after learning skills with an MD or Knuckle bonus.

the stats of the dagger are applied like stats from armor.
the weapon attack of the dagger is only applied to Dagger Skills, which is the only way to actively "use" the dagger.

in the boss menu, below the difficulty setting there is a button to "use support items". tap on it and you get a list of your gems, then select the ones you want to use for that battle.
the selected gems will activate automatically at the start of the battle and their effect is applied to all party members.

=(^.^)=

this should help you understanding weapons: http://toramonline.com/index.php?threads/ultimate-class-guide.26255/