Coat of arms of Weir

The blazon

az. a fesse erm. betw. three mullets, in chief, or, and a crescent, in base, ar. — Crest, a cubit arm, erect, ppr. bolding in the hand a sword ar. hilt and pomel or, on the arm a cross crosslet, fitchee, gu. [Certified, at the College of Arms, London, to James Weir, Esq. May, 1779.]

A blazon is the description of a coat of arms in the technical language of heraldry. The drawing comes from that text, and from nothing else.