Convert from arratel, artel [Arab] to shekel [Hebrew]

Unit Definition (arratel, artel [Arab])
The arratel is a versions of a traditional Arab unit of weight; see rotl. The spelling "arratel" is used in Portugal as an alternate name for the libra.

Unit Definition (shekel [Hebrew])
The shekel is an ancient Hebrew unit of weight (and also a coin having that weight). The shekel was the Hebrew version of a Babylonian unit used throughout the Middle East. Accounts differ on its size. A frequently quoted equivalent is 252 grains, which is equal to 0.5760 ounce (avoirdupois) or about 16.33 grams, but other sources quote a value of 8.4 grams or various values between these two extremes.