It's sung to the tune "Vexilla regis nova." Here's the first musical phrase:
In the third verse, the text here is "Fulfilled is all that David told." "All" is sung with a melisma (B A), lending a slight sense of this entirety.
In the fourth verse, the text - describing "the King of Glory" from the end of the previous verse - is "On whose hard arms, so widely flung" (the sense is continued into the next line: "The weight of this world's ransom hung"). "Widely" is sung with a melisma (A G F#), giving a sense of degree (for the modifying "so"). That the notes are all different pitches also illustrates the word's meaning in a small way.
In the sixth verse, the text is "To Thee, eternal Three in One." "Eternal" is sung with a melisma (C B A G), giving a sense of this duration.
The second musical phrase:
In the sixth verse, the text here is "Let homage meet by all be done." As above, the "all" here is also sung with a melisma (F# E), lending a slight sense of entirety.
The fourth musical phrase:
In the last verse, the text here is "So guide and keep us evermore." As with "eternal" above, "evermore" is sung with a melisma (F# E D E), giving a sense of this duration. "Guide" and "keep" are also sung with melismas (B C and A B, respectively), in a way representing this continuation.
