That move could probably be phrased better. The idea of Defensive Roll is that the Thief is so agile, when he really puts his mind to it he can escape nearly anything, but at great peril. I think the thing that makes the move a little odd is that the fictional bit, the part you have to do for the mechanics to kick in, isn't very clear. I'll need to work on that.
There aren't magic item creation rules, unless you count the wizard's Ritual. This is pretty deliberate on our part, since magic items aren't quite the required part of advancement that they are in D&D 3-4. There's plenty of coolness in just the class moves, magic items are always kind of icing on the cake.
If magic item creation is a route you want to go, I'd talk with your GM and ask about taking the Wizard's Ritual as your move next level. The Thief doesn't have any multiclass moves, but that doesn't mean you couldn't add one.
If there's really a niche for a magic-item Thief, you might also look at what Jonathan Walton (
http://thouandone.wordpress.com/ has been doing with his mini-playbooks (
http://johnstone.wikispaces.com/file/view/AW-valkyrie.pdf/220986434/AW-valkyrie.pdf) for AW that cover specialized versions of a class. They're kind of like AW prestige classes, and we've thought about doing something similar for DW once we finish the basic text.