Let's compare your custom model to the others...
Guardian (Special Weapon(s): Thunder Gauntlets)
- two simple melee weapons (not light) that deal 1d8 thunder damage
- A creature hit by the gauntlet has disadvantage on attack rolls
against targets other than you until the start of your next turn
- As a bonus action, you can gain temporary hit points equal to your level in this class, replacing any temporary hit points you already have.
You can use this bonus action a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
1d8+INT mod per action is really not that good, you do it for the disadvantage and the temporary HP are more like a gimmick. With an enhanced plate armor and shield you can get up to AC 21, taunt the enemy and be a descent tank.
Interceptor (Special Weapon: Lightning Launcher)
- simple ranged weapon, with a range of 90/300 ft, and deals 1d6 lightning damage Once on each of your turns when you hit a creature with it, you can deal an extra 1d6 lightning damage to that target... so basically 2d6 damage
- Your walking speed increases by 5 feet.
- You have advantage on Dexterity (Stealth) checks.
2d6+INT damage for a non-spell range attack is really good
Berserker (at least what I understand)
As part of a shove attempt you can deal yay force damage
As part of a dash you can use a bonus action to make a weapon attack
For every (insert distance in ft) you deal extra damage while performing a dash or shove as mentioned above
while wearing this armour you use INT instead of STR for athletics checks (bc it's pretty much the only strength base ability check)
It's a bit difficult because it's not entirely obvious in which direction you want to go with this armor. The point is the first and last ability... that are both very tempting benefits for a grappler, while the second (and the model's name) is pointing towards plain brutal damage. I'd choose one direction and embrace it.
IMO something you shouldn't mess around with tho: Every Armour Model has its own Special Weapon. Your custom model should fit into that pattern as well:
- simple weapon without any basic features (ie. light), that you can use INSTEAD of a weapon... so in melee it's basically unarmed strikes, except it isn't, so you can benefit from dual wielder
- your INT-mod counts for attack and damage rolls
- a descent effect that triggers on a hit once per turn
- a lesser feature with an effect somewhat influenced by your proficiency bonus, that has no direct synergies with those above
If you want to deal plain brutal damage you shouldn't exceed those 2d6 damage of the lightning launcher, and you gain no other effects... besides something that is equally powered like +5ft movement and advantage on Stealth checks.
As I understand your Berserker you want to play a rusher that deals damage through impact... like a freight train or a raging bull.
So first of all, let's see if there are existing rules for charging...
and there's a monster attack ability that works as followed:
- move in a straight line for at least 20ft
- deal additional damage with the next melee attack
- on a successful hit the target must succeed a STR-save or is knocked prone
AND a feat called charger
When you use your action to Dash, you can use a bonus action to make one melee weapon attack or to shove a creature.
If you move at least 10 feet in a straight line immediately before taking this bonus action, you either gain a +5 bonus to the attack's damage roll (if you chose to make a melee attack and hit) or push the target up to 10 feet away from you (if you chose to shove and you succeed).
To avoid overlapping with this feat, I'd suggest...
- Special Weapon: 1d8 force damage, melee
- once per turn on a hit the target must succeed on a STR-save or is knocked prone (that way we don't have the hassle with Athletics and it fits better with your armor doing the work)
- if you get hit by an energy attack (acid, cold, fire, lightning, thunder) you can spend your reaction to reduce that damage for an amount equal to your Artificer level, you can use this feature for PB/long rest.
Alternatively you could also go with the guardian, take the feats Charger & Dual Wielder, turn your armor through infusions into an Armor of Magical Strength and add your intelligence bonus to strength related checks by spending one of its six charges. You use it to shove someone prone and grapple him afterwards with advantage with your second "weapon" using dual wielder.
Maybe go with that first but talk to your DM and figure something out that you are both okay with and that is somewhat in between a rule-bending(ish) workaround and a home-brewed scratch built. And tell your DM that he or she shouldn't hesitate to change your custom armor if it's overpowered... but to learn, what is overpowered and what's pretty much just descent you should play the "vanilla" armorer first. Then make some ideas of how you want to play the armorer. Have a theme and build around it, first with the rules the game (and your DM) offers you, after reaching those goals you are more experienced (as a DnD player) and are able to better evaluate what changes to the rules could fit your particular play style more.
Just don't make the mistake of doing home-brew stuff to deal more damage. It CAN get you a munchkin reputation even if not intentionally. And I'm not accusing you of that. You have a pretty nice idea for a custom armorer. Now just follow the pattern of the other models and find your way. I'm sure, here are enough ppl who'd be glad to help you with that.