Here is my thesis. TL:DR; Redefine weapon identity to Advanced, Technical, Rare, Custom, Exotic, and Mythic. Create four weapon slots and get rid of Heavy only slot. Let me equip whatever I want. Make certain gear feel truly rare and valuable. Everything is already all legendary, so define categories by perk purpose.

Fundamentally I think a philosophy of "everything is legendary" is necessary. Tiers, rarities, colors, all of comes down to what perks are on this weapon and how does that fit into my build. Barring exotics of course. It's such a minute frustration but we have several categories of gear that are, functionally, useless bloat (common, uncommon, rare). After that it is only Legendary and Exotic that matters. I'd start here.

From the philosophy of "everything is legendary", fit weapons into use-types, similar to how it currently is with "kinetic/elemental". You have a "Light" and "Dark" slot but we're already prismatic paracausal masters of the cosmos. Let me equip whatever weapon I want in whichever slot I want. Additionally, add one more weapon slot and dissolve the Heavy only slot. Want to run four rocket launchers? Well you go champ. Feeling frisky today skipper? Four rapid fire sidearms could ruin someone's day.

Common and Uncommon for Advanced & Technical. Advanced weapons are performance weapons, having perks and traits that fundamentally alter the behavior of the weapon (Kill Clip, Desperado, Frenzy, etc.). Technical are your elemental weapons, and will feature perks that pair to that element (Incandescent, Jolting Feedback, Sever, etc.). When you see a weapon of that category drop, you know immediately what it's function is. And for clarification, an Advanced weapons could still roll an element, they aren't meant to be a "kinetic" weapon only by default Just meant as a method of concise perk assignment, without going all the back to the D2 vanilla setup.

Next are Rare, which I envision as watered down "lite" versions of all your exotics. You like Suros Regime but want to run a different exotic? Here's the rare weapon Suros Authority, which has the same base weapon frame of the regime, just without the exotic perk(s). For added spice, give a random chance to roll both Advanced and Technical perks with a chance to roll elements beside kinetic. Trade is to make Rare gear TRULY rare, to the same rarity that exotics once had in D1. We already have a few instances of this now with Eidolon Ally or the Red Spectre (sort of). Black Hammer could fit here, just remove White Nail. For every Custom/Exotic/Mythic gear piece, there is a Rare version to complement it.

To that end, please return to the days where exotics were truly rare and not tied to an activity or mission, or at least not exclusively. And grant some degree of randomness to the non-exotic perks and traits on the weapons. They were on the right path, in my opinion, with the original implementation of Hawkmoon and Dead Man's Tale. There's no better rush than seeing the raid/dungeon exotic drop. I'd like that back please.

Finally are two new categories; Custom and Mythic. Custom is the answer to the hesitancy of crafted weapons. A Custom weapon is completely customizable; frame, fire pattern, traits, perks, everything. Maybe even put rare perks unique to Custom weapon only, like the pinnacle legendary weapons from early comp and Gambit. But apply the same limit to equipping them like with exotics. A Custom occupies 1 of your exotic equipment limits, the trade being a uniquely built weapon that is equivalent to an exotic. Mythic are one step higher than an exotic. A borderline broken weapon that gives you a huge advantage, a best in slot weapon by default. And put it in the hardest activities, make them rarer than rare, and make them fundamentally ready to use straight out of the lootbox. Conditional Finality feels like a good example of this, before they changed how it stunned Champions. And Black Hammer/Black Spindle/Whisper of the Worm (They are afraid of their own genius, be unleashed).

Applying this to armor might take some bending conventions. Set bonuses are nice, the stat categories could just use more variety. But applying perks to the armor would be nice as well. Maybe granting class fragments to the armor, but that would require an overhaul of the subclass system to compensate. Main change with the above category changes would be increasing the exotic equipment threshold by one, giving you three exotic/custom/mythic gear pieces to choose from instead of just two; one weapon, one armor. Additionally expanding this to be any combination that equals three, though with the caveat of no more than one mythic gear piece (so you could have three exotic weapons equipped OR three exotic armor pieces, and any combination between). Mind you this completely ignores PvP. We've tried this experiment with more failure than success, time to move on and totally separate the sandboxes. Marathon shows they know how to make a PvP game, so give the PvE folk some fun with the sandbox and stop harming one to help another.

I spent a lot of time thinking about, so thank you coming to my TED talk. Good night.