What does "Where every god did seem to set his seal" mean?

A combination and a form indeed/ Where every god did seem to set his seal/ To give the world assurance of a man.
Hamlet shows his mother Gertrude miniature portraits of his father and her present husband, Hamlet's uncle Claudius. In describing his father, Hamlet compares him to the gods Hyperion, Jove (Jupiter), Mars, and Mercury, and concludes his eulogy with a marvelous metaphor which could easily be overlooked. The alliteration in the line "Where every god did seem to set his seal" creates the image of a line of gods, each of whom places his royal seal on Hamlet's father as he passes down their line. Each seal, like the seals of human dignitaries, is intended to verify the authenticity of whatever is being stamped with it. It is, in effect, a seal of approval, or a seal of "assurance." The S sound in the word "assurance" acts like an echo of the alliteration of the three S sounds in "seem to set his seal" in the line above it. The whole purpose of the alliterations is to enhance the mental picture of a virtual assembly line of the famous, immortal gods taking turns affixing their seals to a human being to verify his godlike nature and appearance.