Such clothing is definitely not the clothing of warriors heading out for battle. On the contrary, it is the clothing that John had just referenced in relation to the Bride of Revelation 19:8. This confirms the identity of this army as the saints redeemed by the blood of the Lamb. Note too that whereas the rider of the first horse had blood on his robe, the clothing of the riders of these horses is “pure.” Christ does the fighting; his followers are the beneficiaries.
14 And the armies of heaven, arrayed in fine linen, white and pure, were following him on white horses.