The garb of Death or the black mourning robe, which the first references are found in the early fifteenth century, is very close to the robe of the priest or monk who officiated at the death bed. It is interesting to note that the dead body itself was never garbed in black -- the colour of the winding sheet or shroud seems always to have been white.

The scythe is an image that reminds us that Death reaps the souls of sinners like the peasant harvest corn in his field. Each movement of the scythe brings thousands of souls.

In Greek mythology, Chronos (Cronus) was the king of titans and the father of Zeus.  He was also a harvest god called Father Time and carried a sickle which is a tool used in harvesting grain. The Grim Reaper carrying a scythe are directly derived from Cronus. The myth of Chronos eating his children was used in a poetic sense for time devouring all things, as in the old saying "nothing lasts forever."
The three Greek words that were either related originally or related through confusion later were: Chronus (meaning "time"), Cronus (the god of harvest before the Greek gods took over), and corone (meaning "crow"). Little wonder then that we often see a crow accompanying the Grim Reaper.