explain this mystical creature genetic cross. . .?

Sex linked trait where females are the hemizygotic sex.

Well, since they mention the sex of the offspring, I am going to assume we are talking about sex-linked recessive traits. So these are the parental genotypes:
light winged male means he has just the recessive gene on his one X chromosome
Dark wing female is a carrier because she must pass on the recessive gene to the next generation to be light-winged.
So:   Parents
phenotype unaffected female x affected male
Parents
genotype                      XDXd          V         XdY
Gametes                      Xd and XD                   Xd only
Genotypes
of offspring                  XdXd     XDXd             XDY

XdXd is the light winged female phenotype and XDY - dark winged male