Answer:
C. Ensue means "result from something"
Step-by-step explanation:
"The Faerie Queene" is Edmund Spenser's 16th century epic poem following the story of the knights, each of which representing a Christian virtue, on a quest to defeat evil dragon.
This excerpt describes a sword whose characteristics are improved from an unknown reason.
The character lists some of these "virtues" of the sword stating that he doesn't know from what have they resulted.
So, in this particular case, ensue means "result from something".