Here's another new magical item, based on ones actually carried by mariners.
Medallion of Saint Elmo
More than a few sailors braving the waters of the earth carry some sort of lucky charm; a common one is the medallion of Saint Elmo. Most of these are no more effective than belief can make them, but others have actual benefits. According to legend, these ones are made from lead taken from the very mauls with which Saint Elmo was beaten. Indeed, even more powerful ones are believed to contain one of the saint's teeth, which were removed as part of the tortures that he suffered.
The lesser version of this item provides the effects of a resist energy spell with a caster level of 3; the greater one gives the benefits of a protection from energy spell with a caster level of 5. Both function against electricity and fire only.