Dantalion is credited with reading and changing the thoughts of men, declaring the secret counsel of anyone, and showing the likeness of any person in a vision. He is the clearest instance of a small group of entries whose promises are psychological rather than material.
The group is worth isolating. Alongside Dantalion: several spirits stir up love or hatred between named people; one makes men insensible; one makes men witty; several give the favour of friends and of foes; several sow discord. Set against the treasure, the preferments and the liberal sciences, this is a distinct category of offer, influence over other people's inner states.
The interest is not that the Goetia contains such promises but that it states them so flatly. Early modern legal and ecclesiastical records are full of accusations of exactly this: love magic, the manipulation of affection, the procuring of a marriage, the breaking of one. These were among the commonest allegations brought against cunning folk and among the commonest reasons ordinary people consulted them. The catalogue reads, in this respect, like a price list for services that demonstrably had a market.
Dantalion is also one of the four spirits with no antecedent in Weyer, appearing for the first time in the Lemegeton. So whoever supplied him supplied, along with the name, a set of offices that are among the most socially specific in the book.
That is a small argument against the possibility that the added four are arbitrary filler. Filler tends to be generic. This entry is not: it is detailed, distinctive, and answers to a documented demand.