How to call such system:

The party has shared inventory with unlimited capacity (magic bag). Each party member's worn equipment uses X encumbrance points and when a certain thereshold is reached the member is overencumbranced. So, items when carried in backpack weight nothing but when worn have weight (encumbrance to be more precise) and therefore there is a limit how much a party member cvan weap/equip without penalties but there are no carrying limits of any kind.

To my knowlege nothing like that was ever used in any game. So, I have trouble naming it properly (especially to distinguish it from "items weight system").

Actually, it's an "equipped items weight system" since items in backpack have no weight. You could just call it a "load limit" or "weight limit." Describing it as excluding backpack items, those names would likely be deemed acceptable. 

Just call it weight system... or encumbrance system... or hyperload limit bearing gauge... whatever man it's just a name.

Equiped Capacity

Why do you need to name it? To use ingame you mean? Or is it for the manual?

I think "the load limit for my warrior is 12 kilo" sounds fine. Or in a character screen just: "encumbrance: 7/12 kg. But it also depends on the setting of the game.

If I had to put labels on it, I would think of it as a combination of a warehouse and encumbrance system where the bag of holding functions as the warehouse.
 

21 hours ago, suliman said:

Why do you need to name it? To use ingame you mean? Or is it for the manual?

I think "the load limit for my warrior is 12 kilo" sounds fine. Or in a character screen just: "encumbrance: 7/12 kg. But it also depends on the setting of the game.

I'd introduce to the player the wonderful "magic bag" (or, to call it like D&D, "bag of holding") the characters are equipped with very explicitly at the beginning of the game, maybe in some sort of tutorial, and then reference it in commands ("stash into magic bag", "see magic bag content", "grab random item in magic bag" and the like). Meanwhile worn items would form an almost unrelated system, which could include a display of "load" or "encumbrance" (probably measured in steps of increasing penalties to character performance: "unencumbered", "light load", "slow", etc.) and warnings when objects are too big or too heavy to wear at all or when putting them on or off would change the encumbrance level. Size and weight of each item should be a feature of both inventory displays (worn items and magic bag items).

If the only weight that matters is equipment weight, "equipment weight" or "encumbrance" seems good.  A warrior would likely have far more maximum weight than a wizard.  Many games have similar stats, usually based on a character's strength.

You might consider how NetHack did it as an example, with different effects based on status. Unencumbered, burdened, stressed, strained, overtaxed, and overloaded all have different effects.

The shared inventory, a community chest that doesn't affect characters, and similar in various games. Some like Sacred 2 also let you share items not just inside one game world, but with the Console Hero Chest shared among all characters for the account to shift items between worlds, or you could use it so it didn't encumber your day-to-day inventory space.

On 5/7/2019 at 12:20 PM, suliman said:

Why do you need to name it? To use ingame you mean? Or is it for the manual?

For Steam page description and for presskits

Maybe you should focus on the magical bag (unlimited inventory space!) as the highlight, in addition to the "standard" equip weight system on party members. Then you can use a standard name and a "but wait, there's more" twist.