A Blessing is the greatest gift that a god can give to a mortal. Lasting ten generations, it is a gift of added power or abilities. Unlike Curses, each god can give any Blessing they choose (within the limits of their power, of course.)
An example of a well known blessing is the increased magic which the Royal Family of Thebaz get.
Many blessings come with a "price" of some kind. For instance, the Royal Family, while Blessed with increased magic, are unable to have more than one child.