I'm working on a test item so I can figure out how items work and really how you'd use them, and I can't get the held item image to show, nor get it to be a weapon, or chop trees. I'm not sure if it's still relevant to post on this old thread but I'd like to still try.to ask here. I've seen people helping out others with this issue but for me, I've done it myself as well and it doesn't fix.
Edit; Forgot to mention! The ground and inventory images do work.
blade.zip
In the spriter, you can modify the timeline to make the animation take longer, hopefully this'll help you out.