Being a TSR module (i.e. written for 12 year olds), it really is as simple as it sounds. Take each letter, back up three letters in the alphabet, and voila. Nonetheless, this intrepid chronicler got it wrong between gaming sessions and spent many weeks wracking his brain for an answer.
Amulet 1: | w | k | h | i | d | f | h | r | i | w | k | h | i | l | h | q | g | g | r | h | v | p | r | u | h | w | h | d | q | g | h | y | r | x | u | ||||||||||||||
Translation: | t | h | e | f | a | c | e | o | f | t | h | e | f | i | e | n | d | d | o | e | s | m | o | r | e | t | h | a | n | d | e | v | o | u | r | ||||||||||||||
Amulet 2: | z | l | w | k | w | k | h | o | h | d | v | w | r | i | p | ( | y | ) | i | v | r | p | w | l | v | w | k | h | j | d | s | w | r | a | r | z | h | u | |||||||||||
Translation: | w | i | t | h | t | h | e | l | e | a | s | t | o | f | m | ( | y | ) | f | o | r | m | t | i | s | t | h | e | g | a | p | t | o | p | o | w | e | r |