Armado
The Spaniard Armado is a not so subtle dig at the recently defeated (by the English) Spanish Armada
Berowne
Some believe, as does Asimov, that Berowne is meant to evoke Armand de Gontaut, Baron de Biron, a friend of Henry of Navarre (known in England because of his work with the army of the Earl of Essex, which supported Henry of Navarre)
[btw, the name is pronounced “bahROON” like it rhymes with “moon” (as it does in the play), not “berOWN”]
Longaville
Some believe, as does Asimov, that Longaville is meant to evoke the Duc de Longueville, one of Henry’s generals
Holofernes
This is a Biblical name, but not one ANY parent would use to name a child: it comes from the apocryphal (and Catholic) Book of Judith. Holofernes was an Assyrian general who invaded Judea; he was killed by the titular Judith.