In pathfinder there are a pair of items that I think would fit well into arelith's world and lore, and provide additional solutions to the eternal challenge of all adventurers: inventory management.
These items are the muleback cords, and heavyload belt. The effects of these items is, simplified, to triple the carrying Capacity of the wearer in a way that stacks with the counterpart item. In pathfinder, to triple your carrying Capacity is about +8 strength, which gives us an idea of the power level involved.
The most interesting thing about the items is the choices it forces players to make, as in pathfinder , magical items abilities are tied to slot, which means by choosing to wear a heavyload belt, you are choosing not to have any physical enhancements from your gear. By choosing muleback cords you are refusing the cloak of resistance, alongside all the other powerful alternatives such as the cloak of flying.
I have assembled for your enjoyment an array of objects that increase the carrying Capacity of the wearer, alongside the suggested increase amount and type.
Heavyload Belt: +2 str for the purposes of carrying Capacity, +1 str, and runed. The basic item, with minimal opportunity cost.
Muleback Cords: instead of a cloak, as in pathfinder, i think these should use the body slot, preventing use of other types of armor. In exchange, they grant the largest bonus, fully tripling your carrying capacity (or granting a large flat reduction.
Movable Rod: Mainland item, grants a significant bonus to str. Simple proficiency, and Can be duel weirded, but does no damage, and has arcane spell failure to boot.
Ring of the Encumbered: Budget bead of gravity. Flat weight reduction, easier to craft. Maybe have a greater version that replicates orb, or amulet, but still, you can only have two rings on, so the benefits are limited. Easily swapped, and the lowest bonuses, but rings are fun.
Porter's Boots: +1 end, +2 str for the purposes of carrying Capacity, tracking you is 10 points easier.
Caravaneers Harness(or muleback cords, i guess) : Cloak slot, grants freedom of movement effect, but prevents running. If overencumbered, spawns a cart behind you that follows you closely, Neutral and unhostile to all, but if destroyed, you will drop items unto the ground, heaviest first, until you are no longer encumbered, and the harness must be repaired.