These coins are great indeed!
The Belgian coin is really sharp: I never noticed earlier Mercurius had a small beard. That's the part which was first worn away.
The coin of Luxemburg is part of a series (20,50 and 100 francs). Instead of grand duchess Charlotte, crown prince Jean is depicted. He was grand duke from 1964 until 2000 and abdicated in favour of his son Henri.
The series commemorates count John the Blind of Luxemburg, who was also king of Bohemia and lord of Moravia. He remnants were re-buried ath the Cathedral of Luxembourg in 1946.