I personally a fun of a grid inventories so its a pleasure to find a fellow "grid inventory entrepreneur" that not only implements it but tries to add something interesting and new on top!
That's cool that you can attach even items with other applications (such as keys) to your equip in order to boost characteristics - this paints an image of a tinkerer-survivalist protagonist and i like such things. I even came up with the idea of possibility to attach even daggers and rapiers to armor, so enemies that hit modified in such manner items would get some cashback damage.
Also cool idea with blocking: choosing what to use for block and a lil qte on top to keep you busy.
My overall gameplay experience wasnt smooth - i wasnt able to figure out how to throw or delete collected items away so I quickly ended up with 3 chainmails and wasnt able to pick up maces or halberds. After that i kind a stuck with low stamina and wasnt able to start battles or end turns.
However i was glad to see some fresh ideas and thanks you for sharing tham.
Have a nice day ;)