He is told to “gather the clusters from the vine of the earth.” Whereas standing grain requires that the farmer fell many stalks with one stroke of his sickle, clusters of grapes need to be individually clipped from the vine (in a manner as to leave the vine undamaged for next year’s crop). So the relatively big sickle is not the optimum tool for the task. In this instance, however, there is no need for concern about damaging the vine as this is the harvest of the final judgment; hence a tool can be used that does the job quickly and ruthlessly.
18 And another angel came out from the altar, the angel who has authority over the fire, and he called with a loud voice to the one who had the sharp sickle, “Put in your sickle and gather the clusters from the vine of the earth, for its grapes are ripe.”