The Shield is: Gules five annulets and a canton ermine.
The Crest is: A dexter hand ppr. holding up an annulet or.
The Motto is: "Proprio Vos Sanguine Pasco", 'I Feed With My Own Blood'.
Cantwell is a placename that derived it's name from Old English personal name Cant + wella = stream, spring.
The name of Cantwell is found as a principal name of Tipperary, and is found as well in Kilkenny in the census of 1659. Subsequently, Tipperary and Dublin have become the main locations for the name. Some of the name are of Anglo-Norman origins, coming originally from the name of de Kentwell.
Source: The Book of Irish Families Great & Small
Michael C. O'Laughin
1997 Irish Genealogical Foundation