It likely refers to "your virtues, which are rare, shall..."
Here's a breakdown:
* "Verse": This is an old-fashioned word for "to tell" or "to write". It's used in a poetic sense.
* "Virtues": These refer to good qualities or moral excellence.
* "Rare": This means unusual or uncommon.
* "Shall": This is a modal verb indicating something that will definitely happen.
Therefore, "verse your virtues rare shall" could be interpreted as:
* "Your rare virtues will be told/written about."
* "Your uncommon good qualities will be celebrated."
* "Your unique virtues will be recognized."
The exact meaning depends on the rest of the sentence or the context in which it's used.