Please read a few verses before 16 and notice what is said regarding women, children, cattle, etc.
ok, the verses you are referring to are where God has sanctioned war, using his army as an extension of his arm, to deal out his wrath and justice on the wicked. these are people that can be saved.
the verses i refer to, are for when dealing with people that have such a deep seeded hatred of the children of God, as part of their religion, that there is nothing for them.