Well, first of all you’re designing a melee Strength character, so Sentinel & Primalist are the archetypes it needs to be different from.
For the base skills, Swing sorta sounds like the way Multistrike or even Firebrand works (and I wouldn’t add negative effects to a starter/basic skill), Charge is sort of a Werebear Rampage, Head Bash = Shield Bash, Wall sounds like a Shaman skill akin to Upheaval & Earthquake, Shield Firewall reminds me of Smelter’s Forge. So you’re basically building a Werebear + Forge Guard combo. The Boulder is a nice idea, but it fits the Primalist aesthetic already, especially if you spec full phys Avalanche.
As for the Masteries …
Your Barbarian sounds a lot like a non-minion Forge Guard: a weapons master.
The Beast, that’s just Werebear who can yeet things.
Dragon Knight, firstly wouldn’t fit Intelligence as much if you’re trying to build around dragon magic. As most of the skills you describe here are Shield-related, we’re coming very close to Paladin as well. If we’ld have a Warrior-like class with the above ideas, you’ld probably build this Mastery as a Dragonborn or Sorcerer from DnD (so with Attunement=Charisma) and describe all the different Masteries as his years in weapon knowledge, his dragon ferocity, or his ability to tap into elemental magic as dragon.
Lastly, you’re going way too far into details and complexity. You should first flesh out the base concept, then the generic skills, their key-node changes etc. and only THEN start thinking about numbers and buff effects. A tree has a starting trunk and branches afterwards, a bunch of branches heaped together is just firewood. So start with core ideas first, get a good trunk, then try and add ideas that deviate from that afterwards. Especially all the combos and buffs will just scare off people, introduce it to us like you’ld expect the game to introduce it to players.
Here is how I’ld build up the class:
Dragonborn; Since the Ancient Era, myths have been told about rare unions between Dragon and Human, resulting in a being with the form of a man, but the power of a dragon. It turns out those myths were founded in a source of truth…
Mastery - Artifact Hoarder
The Artifact Hoarder has spent eons travelling, gathering an arsenal of powerful weapons, often regardless of the wishes (or knowledge) of the previous owner. Stand between him and his latest prize and you’ll find out what his arsenal has in store for you! Style: Weapon Master, throw abilities use a chain to recall their precious artifacts. Uses Dexterity & some Intelligence
Mastery - Berserker
Through years of study and meditation, the Berserker has learned to tap into their Dragon blood, altering their body to be more like their ferocious ancestors without losing their humanity. Style: Unarmed(Claws) Barbarian archetype, primal/animalistic buffs here could work with drawbacks, as a struggle to not be overcome with Dragon Blood. Uses Dexterity & Attunement (basically Werelizard)
Mastery - Dragon Sage
For a Dragon Sage, the real treasure is knowledge. Their understanding of offensive magic is beyond even the foolish dreams of men, while their survival relies on the draconic blood that courses through their veins. Style: Battle-mage, I’ld go mostly Fire & Lightning, with Poison conversions more than Ice. Defensively, go more for Endurance/Armor & Block rather than Ward. Uses Intelligence (Offensive) & Dexterity/Attunement (Defensive)
Bonus cosmetic / Unique shield look: A giant dragon scale.
So as you can see, that’s my trunk; a base from which the rest can grow. I specifically tried to add in Dexterity to distance them from Sentinel/Primalist, as it’s currently the stats with only 1 class built around, and as loot lizards have proven, they can be quick & nimble as well. For example, you could have the Hoarder have a fast-attacking melee ability that uses random weapons from his stash, doing random things. You can go a bit more magic-y by replacing the chain with magic throwing the weapon out like a boomerang instead of a straight line. The Berserker could have a passive ability more like Holy Aura or Falcon, where you customize his body to have stronger claws, or thicker skin, better resistance to Dragon Blood …
By now, you’re probably already thinking of ways you could fit your own ability ideas or even new ones into these masteries, even without me explaining a single skill. And that’s the design order you should do.
Once you got the core concept design, you can work on ways to implement ideas into base functionalities. e.g. the Berserker, how do you gear him without weapons? Scale Dexterity into Claw/weapon damage? Or only use weapons as stat-sticks and ignore weapon speed/range, but nothing else? … How can the Dragon Sage / Dragon Knight tie magic & shield together without being Paladin? Paladin is in it’s core melee swings with healing spells, so avoid that overlap with offensive spells (hence no cold spells because Freeze) and use gear scaling to offset. Do you want to scale Block, or just use aesthetic and convert block to DR through passives? … Depending on that last part, you could drop either Dexterity or Attunement for Dragon Sage, depending on the final concept.
If you have your functionality ideas in place, go over the skills again, which ones no longer fit, or just are too complex for players? Which ones are core, what others wouldn’t you mind having access to as other masteries?
After that, well, it’s numbers time, but that’s pretty much a point where you’re ready to implement the class into the game already.
Edit: Cleaned up part on Dragon Knight to be more coherent after a re-read.