and if you look up sinister, one definition is left (handed)
right handed is dexter.
from somewhere on the internet,
Dexter (Latin for 'right') indicates the right-hand side of the shield, as regarded by the bearer, i.e. the bearer's proper right, and to the left as seen by the viewer. Sinister (Latin for 'left') indicates the left-hand side as regarded by the bearer – the bearer's proper left, and to the right as seen by the viewer.