In this flat, the second letter of the first answer word is dropped.  To the remaining letters, add a new letter in the third place to form a word that will answer the second clue.

I felt a frigid _ _ _ _ _ _ as it washed
   across my frame.
A sudden shudder from within - just
   what I couldn't name.
A find with my detector, right beside a
   rusty nail.
I couldn't help but wonder if I'd found
  the holy grail.
Like angels dancing on a pin, I knew it
   was a sign:
A precious sterling _ _ _ _ _ _  ring was
   suddenly all mine.

Answers:

SHIVER
SILVER