Because Holy Lady/Woman doesn't sound as cool.
Something
Holy Maiden? Yeah, that's the best thing I can come up with.
Something
Being chaste is still part of the meaning. Holy maiden just sounds slightly better.
Uh, Consecrated Woman?
"Holy virgin" just sounds creepy as shit.
FGO Supports
Not particularly
x_x
It's because everybody knows that virginity gives you power. Easy. Same rules even now.
BL Character Defining Lines
Originally Posted by successor of the Matou family
..No words can express....
Spoiler:
It's always sounded that way to me. It's like they're being venerated specifically because their hymen's intact- like a more religious, thus more creepy, version of those fat otaku who'll destroy their favourite idol's CDs or melt their waifu's figurines becuse they found out their favourite character and/or idol had the nerve to actually have sex.
FGO Supports
But didnt medievil people also believe semen had holy properties? Thats where the whole "have sex to power up" thing every fantasy eroge uses comes from...
Actually thats more like tantriism