FOR MAGIC: I am a sucker for spellbooks, so what if u had an offhand spellbook ND used ur hand, wand or staff to channel. These 3 options could rank in descending order of cast speed and ascending order of dmg. Just so long as it's not just another ranged option ND actually has some versatility.
PHYSICAL WEARABLE ITEMS: I know I would love trinkets or cloths or armor that fit the style I'm trying to go with, like a bracelet that gives extra luck, or a quiver over my shoulder that gives barbed tips for more arrow dmg.
CUSTOMISABLE WEAPON SETS: A sword set could be, the standard greatsword for more dmg but it's slower to swing, or a saber/rapier that can't knock enemies away or does less dmg but it's lightweight ND swings faster. Crossbow hits harder but a recurve shoots faster. ND if flintlock weapons come out, a musket has more range but is harder to load due to its long barrel, ND the blundy is nice ND short to load but less range.
SET DROPS: What I mean is items suited to certain sets. For example, a whetstone to apply to your sword to give it a bonus dmg. For bows, certain quivers of different arrow types. For magic there could be 1 or 2 spells u start out with but u can find more spell pages or sumthing to expand ur arsenal.
STORAGE/TRADING: I think it might be interesting to have backpacks, not only because there is no reason not to, but also so a trade system where u can sell items u collect to the trader becomes possible. It certainly would make the gold system more fleshed out. Also, nothing is more frustrating than an absurdly limited inventory.
POST NOTE: Sorry if these are too detailed or sumthing, I just can't really put it in a way that's understandable without going a little into detail, I'm just hoping that it sounds cool enough devs will put it in anyway lol.