Malbecco is a very familiar character in literature: The old man who marries young and is then constantly suspicious of his youthful wife. Spenser very likely took the Malbecco-Hellenore-Paridell love triangle idea from The Miller's Tale in Chaucer's Canterbury Tales. We can see this by the way Malbecco is mocked in the poem and kept in the dark---just like Chaucer's old carpenter. However, as Hellenore's name suggests, there is also a connection with Helen of Troy. Helen was the wife of a Greek king, and she was stolen by the Trojan Paris, which initiated the Trojan War. Paridell reinforces this connection by showing that he is descended from Paris; he plans to steal Hellenore just like his ancestor stole Helen.
The discussion of Trojan ancestry also serves another purpose, outside of the poem's plot: to glorify the English nation and Queen Elizabeth. Spenser (and most in his day) would have considered the Trojans the greatest race of ancient times, since they founded Rome, the greatest empire of ancient times. Rome was, thus, called a "second Troy" (as Britomart mentions)--and Spenser links his people with antiquity by calling London a "third Troy." Through the mouths of Britomart and Paridell, he relates the legend that Britain was founded by Brute, a Trojan who fled Troy after he accidentally killed his father. Again, this is historical speculation on Spenser's part--no definitive records exist to prove or disprove the claim. The idea that the British Empire would be greater than Rome seems a bit forced, but it is essential for Spenser's justification of Queen Elizabeth as the greatest of all monarchs. In a more subtle way, this claim continues an argument of Book I--that the Church of England is destined to be greater than the Church of Rome.