Hey Amoeba,
thanks for the detailed questions. Even though I am tight on time I always enjoy to share some of my experience. First of all, the scythe you attached looks pretty good. Just “clean it up” some more and you are good to go. Try not to have too many sharp little details, keep the surfaces rather smooth.
I created a little overview of how I go about creating the different versions of an Icon. The screenshotted photoshop elements are in german, but I am pretty sure you’ll understand what I have been doing.
Cheers!
The second picture shows what happens (to me as well) when adding too much detail and how to deal with that.