The problem with barbarians in the Forgotten Realms is that they lack flavor. The Realms is a hodge podge of different classes, cultures, abilities, and game mechanics that all got lumped into one mass. In an effort to give the Realms a bit of flavor from everything, it gets turned into a vanilla mass where nothing seems unique.
DMs kept saying they disliked barbarian/fighter because they didn't feel the barbarian flavor came through. So barbarians clearly need some definition in this setting so it does come through.
Now, barbarians *could* be normal human meat puppets with a serious overdose of testosterone who can once in awhile enter a "Rage" and smash things with reckless abandon. This is roughly speaking, what the Realms made them and I'm afraid its poisoned a lot of creative minds into thinking barbarians are primitive, savages, who smash things.
You couldn't be further from the truth: Barbarians are based on legends and history, they were the Norse Berserkers.
The Norse, same guys who gave us the legend of Grendel, who found America and colonized it a few hundred years before Columbus, a group of people with a complex religious and magical heritage that is still followed today in Iceland and a growing number of regions in America and Germany. Rome's best generals, Adolf Hitler, and Theodore Roosevelt all were impressed and amazed by these "barbarians".
So I tend to think in a magical setting, even a low magical setting like EfU, that the problem is people can't seperate normal human meat puppets with a serious overdose of testosterone who can once in awhile enter a "Rage" from a group of people with a complex religious and magical heritage .
The solution is to look at how the viking berserkers viewed "rage". Yes, they did view it as a magical gift from the gods. Rage came from Odin and Thor, or from the mystical energy called Wyrd--wyrd was the empty space between magical runes or the silence between syllables of sacred chants and battle cries, it was the calm moment between a battles or at twilight. Berserkers called upon this sacred energy to fight their foes, but also their shamans used it as a magical power to fuel spells, ward off illness, and summon spiritual aid.
So in a world where magic is real, barbarians can vastly improve on this through the use of totems. Totems in this sense are avatars of a barbarian's rage, where it comes from and how it channels this sacred or profane power through them. Its vastly preferable to thinking of barbarians as channeling nothing more than primitive hormonal testosterone, which is why you get bland, dull, lifeless, mindless barbarians so often.
Other settings do this very well. In Eberron barbarians channel their rage through totems, Dragons, Chimera, Pheonix etc. Magical creatures, and with the right feats a barbarian's rage can express itself in magical ways. The Heroes of High Favor series discusses how barbarians draw on rage, for dwarfs its the primal hatred of their collective race for its many foes, for half-orcs its the primal Wyrd the source of passion, anger, and creation-the very well spring from which the orc dieties emerged.
This can make sense in EfU if there are Rage totems, avatars or spiritual manifestations of rage that barbarian tribes learn to draw upon. This already exists to an extent with Uthgardt, but other dieties with specifically barbarian followers can easily fit into this; Urdlen can have a mole totem, Garagos a Wyrd or War totem, even the elemental gods may have elemental totems.
The totems can give minor abilities to a barbarian while he rages, perhaps that even improve as he gains levels:
A bear totem may grant minor DR. A fire totem may cause flames to burn along the barbarian's weapons.
To encourage pure class barbarians, by level 7 these abilities could become fully fledged, perhaps the Mole totem grants Blindsight during a rage and the Dragon or Fire totem causes the barbarian's inner rage to explode in a burst of fiery energy.
Yes, these effects may look more magical: but that's exactly how the ability to rage was originally viewed, legends of berserkers capable of transforming into giant bears that no weapon could harm as they tore apart their foes were common in *this* world, so it'd make perfect sense that in a world where magic is real--rage is a real source of magic.
Its not as good as a wizard, but its there. A seventh level wizard can shoot out four or five fireballs at any foe he wants doing 7d6 damage, while a seventh level barbarian may only cause 3d4 (half his level rounded down) fire damage to *everyone* around him when he Rages. Its got flavor, it would likely encourage more pure class barbarians, and it grants a terrific hook for people roleplaying barbarians.
Various totems could include:
Horse-speed related powers. Wolf/Tiger/Deep Hound-tracking, perception, frightening howl powers. Bear/Rock Lizard-resistance/toughness powers. Dragon/Wyrd-more mystical fiery rage powers Fire, Earth, Wind, Water-elemental powers War, Badger, Wolverine-improvements on traditional rage powers
Its something worth considering. It'll make barbarian more than a class you take just to smash things better while furthering the stereotype of the mindless stupid rager, it adds a magical and mystical dimension to the roleplaying and won't make barbarians better mechanically than fighters who still get far more feats, and abilities with the trade off only a few less points of damage a round (until level 4 where they start doing more than barbs) and slightly less HP and speed.