Arthur, William (1857) An Etymological Dictionary of Family and Christian Names. New York: Sheldon, Blakeman. Public Domain.
WISHART
As described in historical dictionaries
An Etymological Dictionary of Family and Christian Names (1857)
Some ancient writers say, that Robert, son of David, Earl of Huntingdon, took on him the cross, and distinguished himself in the Holy Land, where, from his gallant exploits against the Saracens, he received the name of Guishart, that is, Wise-heart, now Wishart.
Patronymica Britannica (1860)
WISHART. Perhaps the old personal name Guiscard. This seems likely, from the mediate form Wiscard in H.R.
Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.