Summary
"On the Death of Sir Roger Manwood" is a short poem commemorating the death of a great man, a Baron of the Exchequer. This man was also a judge at one point in his career, and Marlowe had been brought before him for offenses against the law. It seems odd that Marlowe would write about a man who had held the power of law over him, but Manwood had been lenient (Marlowe believed justly so) and Marlowe revered him as a great man. Manwood was Kentish in origin, and Marlowe may have respected him as fellow countryman.
He calls him the "terror of him who prowls by night" -- that is, a crusader against the evildoer. He is a "Hercules", by which we may believe that he is either very strong in body, or strong in moral character. These classical allusions are common in Marlowe's poetry.
The predatory imagery continues, when Manwood is called a "bird of prey" (vultur, in Latin) "upon the rough brigand". This is an unusual way to think of a magistrate and an official of the government. Instead of portraying him as a staid upholder of the status quo, Manwood is shown as active and violent in the prosecution of justice.
"The light of officialdom, the glory of the worshipful law, lies dead" he says of Manwood. For a man who ran so afoul of the law so often in his life, it seems odd that Marlowe would use these terms to describe authority. It may be the Marlowe was ironic, but more probably he was imitating the style of Roman epitaphs of this same type. Marlowe often imitated classical culture in all its forms, and he wrote this epitaph in both Latin and English.
The poem ends more conventionally as a eulogy, "On these terms, when Death's pale messenger wounds you, may your bones rest happily, and may your fame survive the memorials of your marble tomb." This is more like what people say about the dead, and particularly people who did great and worthy things during their lifetime. There is no mention of the Christian god, but instead there is a reference to the classical idea of Death's pale messenger. The only comfort (as Ovid had so often put into his own poems) was that there might be fame after death -- no mention of the afterlife is made.
Analysis
This poem must be taken as sincere, for Marlowe probably would have not written a eulogy of this type for so exalted a man. If his meaning was different than the poem expresses, it is deeply encoded. Probably Marlowe did admire Manwood, and took the oppotunity of his death to express his feeling in a way a man like Ovid, whose poetry he had translated, would have expressed it sixteen hundred years before Marlowe wrote. This epitaph form is indeed an old one, and Marlowe was fond of imitating old forms (such as the pastoral, The Passionate Shepherd to His Love, and the epic Hero and Leander.
In his poetry Marlowe had translated two major classical authors' works (sixteen and fifteen hundred years old at the time he translated them), a pastoral love poem of a type at least seventeen hundred years old, and the story of Hero and Leander that dates from well before the Roman or even the Greek Empire. It is fair to say that, at least in his poetic forms, Marlowe was backward-looking. His subject matter, and treatment thereof, was refreshingly modern and sometimes even shocking, but he preferred to take much of his subject and form from the distant past.
Considering that drama in England was still very new (apart from the religious plays of the Middle Ages, this was the first time one could go to see a play in London in a form that we would recognize as "a play") it is interesting to note that Marlowe took his poetry backward, but his playwriting to the cutting edge. Playwriting was a risky business in some respects -- there was always the possibility that theatres could be shut down. This happened several times during the Elizabethan age, as the city of London would experience a kind of Protestant revival and decide that plays and playacting were sinful. The famous theatres of Marlowe's (and Shakespeare's) time actually lay just outside of the official bounds of the city of London, so to avoid the censure of city officials. Looked at this way, it seems that Marlowe was perfectly willing to walk the literary edge in writing his plays, but when he wrote poetry (in poetic form, at least), he preferred to return to old favorites. This was a common practice in the Renaissance, and the rediscovery of classical authors and culture was what fueled much of this time of great creative and scientific change. For Marlowe to take the words of the past and put it into his Elizabethan venacular was a work of homage to the past, but also a work of belief in his own time. He must have had readers for his classical works, and he found it a worthwhile pastime to put old poems and stories into Elizabeth English.
So for Marlowe to write an epitaph in Latin to a great figure, whom he admired, was perfectly in character; for him to translate it into English was also in character. Marlowe did live in two worlds. He was a product of the Latin-bound society of scholars at Cambridge, and also a playwright of the vernacular in London. With this poem he straddles both worlds, and pays homage to a contemporary figure within the sensibilities of the classical past.