Grim reaper is a skeleton in a black cloak, holding a sickle. This is an allusion in the West. In the Bible, Jesus compares believers to wheat. When the time comes, they will harvest (enter heaven). Therefore, harvest has become the pronoun of death in the west, and the sickle has become the weapon of death.
As a reaper, the powerful tool is the sickle, which is connected with farming. But the one that came to the East didn’t mention death’s weapon in detail. In this regard, the evolution and origin must be traced back to the development of sickle.