I'm doing the fighters guild quest from Ald-Ruhn where you have to go clear the necromancers in Vas. and in there I have encountered some dunmer (I think) in black armor with red borders. Every time I try to attack them they get this bubble around them and I can't hurt them. To this point I havn't really done much with magic, and most of the quests I've done have been stealth related, so I was wondering what I need to do so that I can attack these guys and actually hurt them.

Wait till the shield wears off.

If your weapon skill is high enough to hit on a regular basis.
don't stand and hack at a fast pace, hold the right mouse buttun down
a few sec. and give it a big hit. I have a 100% long sword skill and ebony long sword. most of the real enemies don't last through the
3rd big hit. oh yes, what type of weapon do you have. did you notice
that the iron and steal stuff are ineffective on higher beings, so you have to use better stuff along the way.

ill answer this one correctly for ya.
the char you are fighting is a dremora and or dremora lord. most notably they are immune to normal weapons. are weak to fire.dremoras have 160 hit points and are generally mage types. using all spells till magicka runs out. they genarally carry weaker weapons such as dwarven and dwemer type weapons. dremora lords are more like fighters they carry a whooping 280 hitpoints and generally carry deadric and ebony type weapons. if under lvl 15 they are more prone to carring weapons like the dremora so as to make your buttkicking less physical.

the standard dremora carries a 2nd barrier spell and reflect.

dremora lords carry 4th barrier, reflect andfire storm.

the main key to killing a dremora/lord is you gotta have a magical weapon to kill them