Her stepmother made a Princess a Ladily Worm by her spell. Three kisses of the princess's brother could make her return original shape. This was said when her brother was going to fight a Ladily Worm, which is the princess.
"O, quit your sword, unbend your bow,
And give me kisses three,
If I'm not won ere set of sun ,
Won never shall I be."
This is from a English fairy tale "The Laidly Worm of Spindrestone Heugh". Why is this sentence "If I'm not won ere set of sun" passive form?