The problem we decided not to have
Anyone who has played MMOs for long enough knows the scene: the bag is full, and the same question repeats a thousand times — do I keep it or sell it? It never gets easier, because there was never enough information to answer it. That is not a decision; it is noise. The rule we adopted is simple: if the player needs a wiki open to know whether an item is any good, the item is badly designed.
Rarity is not in the item — it is in the creature
This is the inversion that organises everything else. In ESVA, what is rare is the esva. Two with the same name are worth different prices because of band and IVs, and that is where collecting happens — not in a drawer full of junk. Field items are deliberately predictable: every class drops the same set — fragment, core, relic, reagent and apparatus — separated by tier according to the incursion they came from. You learn it once and you know it forever: this feeds a profession, that one goes straight to the counter.
The few exceptions, and why they exist
Rare items do exist, but each one pays for its own space. The Rupture Reagent only comes out of the Cavern, and it is the only material capable of breaking an esva's form. Cosmetics are cosmetics and never touch the maths. And there is the Boss Egg, which comes from the Boss Arena — future content, three-player co-op (one tank, one healer, one damage dealer) or solo, in real time. None of this is a list of three hundred consumables with similar names: it is a few things, each with a reason you can explain in one sentence.
Even decoration does not live in the bag
The farm takes the rule to its limit. It is future content and deliberately light, for players who enjoy collecting. Every decoration arrives as a scroll — one you earn, one that drops, one you buy. On use, the decoration is recorded on the account, and you place it and remove it freely on the farm map: it never takes up space, never becomes an inventory line. If you want to sell it, you sell the scroll while it is still unused, and whoever buys it is the one who uses it. And since only one binds per account, the second copy necessarily goes to the market — which keeps supply alive without filling anyone's bag.