Some guidelines from our world:
“Until the late 20th century U.S. age of consent laws specifically names males as perpetrators and females as victims. Following English law, in which the age was set at 12 in 1275 and lowered to 10 in 1576, ages of consent in the American colonies were generally set at 10 or 12. The laws protected female virginity, which at the time was considered a valuable commodity until marriage. The theft of a girl’s chastity was seen as a property crime against her father and future husband. If two people were married and had sex, no matter what their age, no crime was committed because a woman was her husband’s property. In practice, too, the consent laws only protected white females, as many non-white females were enslaved or otherwise discriminated against by the legal system.” --Sex and Society, Volume 1 page 54.
Based on this, it would not be unusual for your blacksmith to have a 13-yo wife.
Side note: Juliet was 13 but Romeo's age was only described as "young."