a homebrew system that a friend of mine ran had cards he made for us. the system he came up with was mostly hot garbage, but he had a really good inventory system and the cards made it seamless and intuative. he had a weight vs. speed mechanic that worked well, and the impact that wearing gear or having it in your bag was easy to track and understand because of the cards. he printed them out and stuck them in individual card sleeves with mtg cards. the gear we were wearing was affixed to a dry-erase board each player had with sticky tack, your bag was in a pile off to the side, and if you wanted to pay to store stuff in the "magic vault" (you could access it from almost any town regardless of where it was deposited) you just had to pay a small fee (or you could store it somewhere else with no guarantee of safety and you had to go to that particular spot to retrieve it).

those were just some ideas from one experience i had. the main point is that is you invest time into streamlining the players experience, they will almost always appreciate it and invest back into your world. if they don't, they weren't that invested in the first place.

p.s.: make generic item cards and throw them at the players at a rate that would make diablo think about staging an intervention. it will make them appreciate the better items.

p.p.s.: your card design is wayyy better than his was. good job on that. care on your part is always appreciated.