The theological treatise discusses various theories on the origin of witches - which isn't really known but the book insists is surely part of God's design either way. Witchness doesn't run in families. Occasionally some witch's granddaughter is also one, but nowhere near consistently. So therefore witches are clearly chosen somehow. The basic powers of witches seem angled towards fighting, but there's no real reason they should be associated with the cadre of angels whose job is to punish evildoers - while blessed and magical, they are still of the flesh, not pure and divine like angels. There are long litanies of various sides of the argument.
You get iron out of certain kinds of rocks! You have to heat them up very hot in a special container, far hotter than a normal camp fire could achieve. This gets you a mush of iron with gaps in it, which you hammer down into a solid bar. It's weaker than proper-forged iron but proper forging takes a fire that's even hotter and most smiths can't do it themselves. It has pictures of the rocks, and of the iron-making tools, and describes what to do with the non-iron goop and gunk that you get from the rocks (seal it away carefully, it's pretty poisonous).