Learning to Tank

[Moirear]

Well the archer in my group was level synced. So is it really ok, to let that mob go to them and not worry about it? Would they be able to handle it and not die?

BTW, since I got a level 34 CNJ/WHM it makes sense that I go GLA then PLD. But is there skills I should try to get from the marauder?

I'd get them all. CNJ only gives you one worthwhile cross-class ability for the endgame, and that's Stoneskin because your Mind stat is irrelevant to its efficacy. The rest are pretty much useless: Raise cannot be used in combat, Cure is too pathetic because of insufficient Mind, and Protect is eclipsed by a WHM's Protect. The MRD abilities on the other hand are all inherently useful to a PLD to varying degrees; they give you a DoT (Fracture) which actually supports enmity generation, an extra defensive cooldown, a self-healing ability based on damage you inflict, and an off-global-cooldown finishing move that might heal you if it lands a killing blow. And you only need MRD26 to unlock them all.

On a personal note, I recommend taking both tank jobs all the way to 50. You will learn a lot about both of them individually and how to work together with a different type of tank in 8-player duties.

All the dungeons up to, roughly, Haukke Manor or Brayflox's Longstop are designed in a way that no role has to be played in a completely solid fashion. Perfect role mastery only speeds up their completion. So yeah, if you lose top enmity to an archer now and then, it won't be the end of the world. You'll get more and more tools to deal with it as you progress, but generally, it's never easy at the lowest level dungeons unless you outgear the dps players. They might need to learn the hard way that pew-pewing targets only after a tank establishes adequate threat or only going full out in the right moments is also their shared responsibility in the grand scheme of aggro management.