My mom's big hobby is Civil War reenacting. She regularly puts on a big ole skirt (that she hand sewed herself). For a while she's wanted me to knit her a sontag. It's a little like a cross between a shawl and a vest. It covers your back and has pieces that cross over your front and tie around your waist.
I was resistant to taking this project on because there is not an exact pattern: like many historical patterns it's more of a sketch of how it's done than something that takes you by the hand, telling you finished measurements and how many stitches you have at all times. Sigh. I have just had to let go and go with things.
I helped mom choose a beautiful merino Knit Picks DK yarn in hollyberry, with fedora (brown) for the crocheted border. Next, I chose a stitch pattern from Barbara Walker's A Treasury of Knitting called "diagonal weave." This is a slip-stitch pattern that looks a lot more difficult than it is. I expect it will be very warm!