ETYMOLOGY
irregularly formed on Latin dexter (on the right hand or right side) + -ic + -al
EXAMPLE
“… It is called of the Hebrewes, … the hande of the Soule, or … the right hand of the minde, because it makes any conceit dexterical, one of the two things, for which a pregnant Poet (as imagine of Homer, Naso, or any other) especially is to be admired: …”
From: The optick glasse of humors.
Or The touchstone of a golden temperature
Or, The philosophers stone to make a golden temper.
By Thomas Walkington, 1607
Lexicophilia 