The claimed "Dragon's Eye" symbol based on the depiction in Rudolf Koch's Book of Signs: An isosceles triangle, which is approximately intermediate between a right isosceles triangle (i.e. half-square) and an equilateral triangle, and which is divided by internal lines into three approximately equal areas.
Own work work based on copyright-ineligible geometric design in book by Rudolf Koch (died more than 70 years ago)
AnonMoos