salve n.

1640s, "payment for saving a ship from wreck or capture," from French salvage (15c.), from Old French salver "to save" (see save (v.)). The general sense of "the saving of property from danger" is attested from 1878. Meaning "recycling of waste material" is from 1918, from the British effort in World War I.

An allowance or compensation to which those are entitled by whose voluntary exertions, when they were under no legal obligation to render assistance, a ship or goods have been saved from the dangers of the sea, fire, pirates, or enemies. [Century Dictionary]

"medical charlatan, impudent and fraudulent pretender to medical skill," 1630s, short for quacksalver (1570s), from obsolete Dutch quacksalver (modern kwakzalver), literally "hawker of salve," from Middle Dutch quacken "to brag, boast," literally "to croak" (see quack (v.)) + salf "salve," salven "to rub with ointment" (see salve (n.)). As an adjective from 1650s.

The oldest attested form of this quack in English is as a verb, "to play the quack" (1620s). The Dutch word also is the source of German Quacksalber, Danish kvaksalver, Swedish kvacksalvare.

A quack is, by derivation, one who talks much without wisdom, and, specifically, talks of his own power to heal ; hence, any ignorant pretender to medical knowledge or skill. Empiric is a more elevated term for one who goes by mere experience in the trial of remedies, and is without knowledge of the medical sciences or of the clinical observations and opinions of others; hence, an incompetent, self-confident practitioner. A mountebank is generally a quack, but may be a pretender in any line. Charlatan (literally 'chatterer') is primarily applied, not to a person belonging to any particular profession or occupation, but to a pretentious cheat of any sort. [Century Dictionary, 1897]

 Also "one who pretends to knowledge of any kind" (1630s).