I think this is the best ever artistic depiction of Satan.
Conventionally in art, Satan is portrayed as an ugly red creature with horns and cloven hoofs. While the red colour and horns have foundation in Revelation 12, a more accurate portrayal based on that text would probably be of a serpentine creature, a giant snake, rather than an humanoid figure.
Dore departs from convention in drawing Lucifer as an handsome angel. This reflects the Biblical idea of Satan as an angel.
17 Thine heart was lifted up because of thy beauty, thou hast corrupted thy wisdom by reason of thy brightness: I will cast thee to the ground, I will lay thee before kings, that they may behold thee.
Often sin is attractive to the eye. That is because so often it is a corruption of that which is good. Sexual sin is attractive to people because it is a corruption of the divinely created blessing of marital sex.
Let us beware of false teachers. So much in false religion is attractive. The worship in Roman Catholicism and Eastern Orthodoxy is beautiful and majestic, yet this facade betrays an ignorance of the Gospel. The evangelists of cults come across as pleasent, sincere and knowledgeable in Scripture, yet they present a message that contradicts the truth.
Note that Lucifer in this picture has been wounded in battle with God's angels and he is armed for war.
There are battles in heaven. We do not understand everything about these battles. We do not know what weapons creatures with ethereal bodies would use or what effect these battles have on this world, but we know they are fought.
7 ¶ And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
Christians do not directly engage in warfare with fallen angels; if we did we would have no hope of victory, for they are greater than us in power and strength. However, through our prayers we fight against them. By preaching the Gospel, we bring men out of the captivity of Satan's kingdom and the domminion of his counterfeit heavenly government.
12 For we wrestle not against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this world, against spiritual wickedness in high places.
Notice that Lucifer's feet are bare. Dore always portrays his angels with barefeet. No doubt angels have no practical need for shoes, as they live in the perfect and ordered realm of heaven. However, their barefeet reflect the fact that they dwell in the very presence of God, the holiest part of the universe.
Satan once dwellt in the presence of God. We read in Ezekiel 28:
13 Thou hast been in Eden the garden of God; every precious stone was thy covering, the sardius, topaz, and the diamond, the beryl, the onyx, and the jasper, the sapphire, the emerald, and the carbuncle, and gold: the workmanship of thy tabrets and of thy pipes was prepared in thee in the day that thou wast created.
14 Thou art the anointed cherub that covereth; and I have set thee so: thou wast upon the holy mountain of God; thou hast walked up and down in the midst of the stones of fire.
15 Thou wast perfect in thy ways from the day that thou wast created, till iniquity was found in thee.
16 By the multitude of thy merchandise they have filled the midst of thee with violence, and thou hast sinned: therefore I will cast thee as profane out of the mountain of God: and I will destroy thee, O covering cherub, from the midst of the stones of fire.
That Satan fell into sin having dwellt in the very presence of God is a lesson for us.
The Christian posesses eternal life. She lives a divine life and is indwellt by the Holy Ghost. Spiritually her identity is in heaven. Yet Christians so often fall into sin, even though they have experienced God. We can fall away. We can grieve the Spirit of God. Let us not have a false confidence, but let us walk with humility and exercise moment by moment faith in Christ for His sanctifying work through the cross.