I would agree that the mythology that has come to characterize Satan has certainly clouded any resemblance to his true nature, and has served to perpetuate wild imaginations to the understanding of certain scripture. Satan is most certainly the accuser, as the book of Revelations declares:
Rev 12:9-10
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
10 And I heard a loud voice saying in heaven, Now is come salvation, and strength, and the kingdom of our God, and the power of his Christ: for the accuser of our brethren is cast down, which accused them before our God day and night.
But Satan is more than simply the accuser of our brethren, Satan’s power comes from the Law, and without the Law, he is nothing. In fact, Satan could be looked at almost synonymously with the law, for it is the law that accuses us. Now before anyone flies off the handle here, Satan is not the only one who was identified as the accuser; Jesus identified Moses as the accuser.
John 5:45
45 Do not think that I will accuse you to the Father: there is one that accuseth you, even Moses, in whom ye trust.
I don’t think there are many that would argue that the law isn’t synonymous with Moses, just as it is with Satan.
Now if I may take a little liberty, there is an analogy here for those who see who see the King of Tyrus in Ezekiel 28 as a type for Satan. We are told that he was the anointed cherub that covereth, and that he was perfect in his ways until iniquity was found in him. In looking at the law, it was seen as perfect, yet a flaw was found in it: the law in and of itself could not give life, only death. In this archetype, the anointed cherub covered the mercy seat, or in other words, sought to hide or prevent mercy. Yet through the law and the prophets we know that God demanded mercy.
Micah 6:8
8 He hath shewed thee, O man, what is good; and what doth the Lord require of thee, but to do justly, and to love mercy, and to walk humbly with thy God.
But mercy does not come from the law, mercy can only come through faith. This was demonstrated through the ministry of Jesus:
Mark 2:6-10
6 But there were certain of the scribes sitting there, and reasoning in their hearts, 7 Why doth this man thus speak blasphemies? who can forgive sins but God only? 8 And immediately when Jesus perceived in his spirit that they so reasoned within themselves, he said unto them, Why reason ye these things in your hearts? 9 Whether is it easier to say to the sick of the palsy, Thy sins be forgiven thee; or to say, Arise, and take up thy bed, and walk? 10 But that ye may know that the Son of man hath power on earth to forgive sins.
Matt 23:23
23 Woe unto you, scribes and Pharisees, hypocrites! for ye pay tithe of mint and anise and cummin, and have omitted the weightier matters of the law, judgment, mercy, and faith: these ought ye to have done, and not to leave the other undone.
I could go on and on with scripture in the vein of judge not lest ye be judged, and yet that is the essence of our battle against the principalities and powers, it is a spiritual battle concerning the law; which bring us back to Satan and the law as our accuser. When we try to walk by the law according to the flesh, it is easy to develop a sense of self-righteousness and pride, and then we take on the role of accuser as we condemn others for not following the law, when in fact the law according to the flesh should form in us a sense of humility.
James 4:7-11
7 Submit yourselves therefore to God. Resist the devil, and he will flee from you. 8 Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded. 9 Be afflicted, and mourn, and weep: let your laughter be turned to mourning, and your joy to heaviness. 10 Humble yourselves in the sight of the Lord, and he shall lift you up.
11 Speak not evil one of another, brethren. He that speaketh evil of his brother, and judgeth his brother, speaketh evil of the law, and judgeth the law: but if thou judge the law, thou art not a doer of the law, but a judge.
Jude 1:8-10
8 Likewise also these filthy dreamers defile the flesh, despise dominion, and speak evil of dignities. 9 Yet Michael the archangel, when contending with the devil he disputed about the body of Moses, durst not bring against him a railing accusation, but said, The Lord rebuke thee. 10 But these speak evil of those things which they know not: but what they know naturally, as brute beasts, in those things they corrupt themselves.