What does this quote in Don Juan by Lord Byron mean? "Sweet is a legacy, and passing sweet The unexpected death of some old lady"

Question

Sweet is a legacy, and passing sweet The unexpected death of some old lady

I saw this quote in C. S. Lewis's The Inner Ring and I'm having trouble figuring out what it means. What does this quote in Don Juan by Lord Byron mean?

Answer 1

It means, "To be left money or property is sweet (pleasant/agreeable/nice) and the unexpected death of an old lady is extremely sweet (pleasant/agreeable/nice)."

I'm glad to see the poem continues more even-handedly!

Or gentleman of seventy years complete,
     Who've made 'us youth' wait too--too long already
For an estate, or cash, or country seat

[ Stanza CXXV ]