Hey, tell that to Cubicle 7, but when you look at the archetype on paper, it works. Also note, there's no ''barbarian'' in AiMe, the class is called Slayer and it removes the more animalistic/wilderness theme of the barbarian.
The foe-hammer can benefit from Rage while wearing heavy armor (and gets to add their dex bonus to heavy armor, which is OP as hell and wouldnt port to regular 5e). IIRC, the archetypes can use a BA to bash enemies with their armored fist while raging, can auto-crit X/long rest and can break shield and armor by sundering their weapon. Think like ASOIAF's the Mountain had a baby with 4e Essentials's Slayer.
The rider has a damage bonus when charging or when mounted. It also has bonus with thrown weapon, dealing max damage when rolling with advantage and ignoring long range if mounted. At higher level, they can sound their horn to share the bonus from rage and reckless attack with their party for a round and have the same Intimidating Presence as the PHB Berserker.
For the Thane barbarian (leader), I'd go with the shou-ty archetype. Use war cries to boost allies and debuff enemies.
For the Hurricane (dual-wielding barb), I'd take Mearl's idea for ranger correction from Happy Fun Hour, mainly its new weapon style, Whirling Blade.
''When you engage in two-weapon fighting while wearing light or no armor, you do not expend your bonus action and add your ability modifier to the second attack. You can still gain the benefits of two-weapon fighting once during your turn. ''
Maybe add a somekind of ''attack on the run'' feature where you can attack every creature within X once without triggering AoO as long a you hit X per day, like a martial version of Chaos Bolt. If you go the with the Dervish theme you could also add fire and heat resistance or stuff like that.
