Recently, I've been playing with the play style and set Izola suggests from the hall of heroes. The clockwork guardian gameplay suits around a slow and patient style of play that is more lenient on mistakes at the cost of viability. My loadout was a full Ironmight set with Sudaruska and Iron Slug however the Attack Speed medium decrease was a bit cumbersome with the sword; so my armory now consists on Ancient Plate mail and Divine Veil for general purposes.
I find that it is most effective to treat this loadout like a bomber without bombs. I.e; rely on the powerful charge attacks of your weapons. The main source of damage are from magnus weapons (like Iron Slug), given their ability to plow and deal multiple instances of damage when dragged by the bullet. The Sudaruska was effective in pushing enemies off you and, when charged, capable of nuking groups when aimed well (it also doesn't trigger defensive responses like Mecha Knights shielding or Wolver dodges). I also played with Brandish styled weapons like the Combuster and they prove decent for damage and close ranged combat if heavy melees are too cumbersome to use. Bombs are also quite handy for this as they don't suffer from the attack speed decrease, although I recommend using vaporizer or vortex style bombs for supporting the team or yourself.
What I found worthwhile from this playstyle was the Stun resist was actually alright when fighting certain mobs. Greavers come to mind as getting stunned by them can be detrimental especially in Fiendish environments. Resisting hits from lumbers and, more effective, trojans was also alright but they should be dodged rather than tanked. Running through T2 becomes even more of a breeze as you can tank literally any hit without much punishment.
The main drawback to this play style was its lack of viability. Its quite obvious that other superior playstyles surpass this in terms of effectiveness, especially the Chaos set and Wolver sets in terms of elimination speed. Its also note worthy that the extra normal defense these armors provide are quite redundant in T3 as enemies in that tier begin dealing pure specialized damage so it would be more beneficial to wear other armors rather than the guardian set. Fighting against fiend becomes more problematic against this style as their agility counters the slow attack speed decrease and makes them even more of a chore to deal with.
Personally, I like the guardian playstyle for the memery of it all. Sure, its not as effective as other conventional loadouts, but its got style. Running around in heavy bulky gear and absolutely hammering everything (well except for devilites) can be quite satisfying especially when bunched up in groups. I'd not recommend playing this style as its quite difficult to get into, less effective and, although you may be allowed more mistakes, will suffer more mistakes from its clumsiness.
If there was one thing I would change about these armor sets would be to double down in its tankiness for 5 star armors, like an additional +2 health bars for plate sets or even a flinch resist low on helm and armor from damage as the armors would benefit to subside the attack speed decrease.
When looking at the "guardian" items, you have to separate weapons, armor sets and shields.
The shields are both fine, no real comment. You can't do much wrong with shields either though, so whatever.
The armor sets are straight up bad. Not only can the heavy-hitting playstyle be done better with glass cannon gear (and some trinkets/perks to either raise health or mitigate statuses) like you suggested, but the armors are also objectively bad in terms of stats.
You get pretty high normal defense and kinda low elemental or piercing defense, afaik a similar amount of defense, if differently distributed, to other defensive armor sets like Grey Owlite and Dread Skelly.
In return for lacking the (as you also said) for T3 somewhat more useful specialized defense you get reduced attack speed, a severe sleep weakness and the Ironmight set doesn't even have two status resists.
So if you want to tank, which is already not the best idea, you just have straight up better choices stat-wise. I don't know how to fix Plate, but it'll need more than a few pips of health.
The weapons...
Magnus-style guns are pretty good after the rework. Iron slug deals normal damage, Callahan has the wrong damage type for a lot of things and the Winter Grave freeze feels counterintuitive most of the time, but all three are entirely usable at worst. The basic fire has an amazing flinch rate with acceptable damage, with a charge attack that is the gun equivalent of the brandish line.
Troika-style swords (Sudaruska, Triglav, Node Slime Crushers) are kinda bad, but not as awful as the Ironmight armor set. What I don't get is why the charge attack smash is divided into two hits instead of being one big burst of damage, but I am no game designer. I don't think any change can make them even close to meta outside of grossly overinflating damage numbers, but I also don't think every weapon has to be meta.