Jordan uses many mythological and historical sources for the Forsaken. Some etymologies are more clear than others. I'll go through each of them:
Aginor: Aginor was a character in the Iliad who attacked a stronger opponent (Achilles) and was defeated, similar to Aginor's own demise.
Aran'gar: Etymology explained in the series as a type of blade.
Asmodean: As you acknowledge, comes from the demon Asmodeus.
Balthamel: This article draws parallels between Balthamel and Dionysus.
Bel'al: May come from בליעל Belial, which means worthless in Hebrew. In the Bible, "sons of Belial" is used for evil men. (eg Deut. 13:14) (Source)
Cyndane: Etymology explained in the series as "last chance" in the Old Tongue.
Demandred: This site says that Demandred is the name of one of Arthur's knights; however, I cannot find that anywhere else.
Graendal: I'm not sure. It may be related to Grendel, a villain in Beowulf, but I don't see much similarity.
Ishamael: From Ishmael, the name of Abraham's first son by Hagar in the Bible. (Gen. 16:15)
M'Hael: May be a reference to Michael, the archangel in the Bible, coming from Hebrew מיכאל Mikha'el = "Who is like God?" He's the enemy of Lucifer, the morning star, who might be Lews Therin, Lord of the Morning.
Lanfear: From l'enfer, the French word for "Hell." Selene is probably related to the Greek moon-goddess by the same name.
Mesaana: From here,
Possibly from Messalina, the notorious third wife of Tiberius Claudius Drusus Nero Germanicus, Emperor of Rome. Jose Abrigo observes that there was actually an ancient city called Messana, whose civil war was the catalyst for the First Punic War between Rome and Carthage.
Moghedien: Etymology explained in the series as "spider" in the Old Tongue.
Moridin: It means Death in-series; however, it might be a reference to Mordred from the Arthurian legend.
Osan'gar: Etymology explained in the series as a type of blade.
Rahvin: The wiki says that he may be based on a Hindu demon Ravana. His alias Gaebril is probably based on Gabriel the angel.
Sammael: Might be related to the prophet Samuel, but probably closer to Samael, a biblical archangel who, according to Wikipedia, has been seen as both good and evil.
Semirhage: Possibly based on Semiramis, a legendary Assyrian queen.