This was so good. Inventory management done right and in a really fun way. The only thing to improve might be to add accomplishments, but it's already great.
Also, maybe having a thing that explains how the bonuses work. I did go into battle with the bow 3 or 4 times before I figured out how the arrows had to be next to them. (I think one of the bows said adjacent arrows would get +4 and either I didn't understand how it worked, or it malfunctioned.)
But seriously, hours of fun. Great job.