Ah, the office cardigan. Unless you're working from home in your yoga leggings and tank top, swaddled in a quilt of your choosing, the only way to combat frigid cubicle temps is to BYOC. As a rule, an office cardigan should consist of good, non-pilling fabric, warm but not parka material, and should look like it can go with any outfit as a conscious decision, not a confused afterthought. Because you never know when you'll get pulled into some kind of project meeting, and you don't want to be bundled up in an electric purple Victoria's Secret PINK hoodie, zipped up to your chin.
Not that I'm speaking from experience or anything.
The blouse I'm wearing today is actually this one, currently on sale at Ann Taylor. The jeans/pants I'm rocking are $39 BDG cigarette pants from Urban Outfitters, and my office cardigan is a grey crew neck from H&M, which regardless of its non-cashmere status, does not look like an afterthought. And those Madewell sandals might be the best purchase you make all year. You heard it here first.