You must be very brave, or very desperate -- or both -- to attempt sweater surgery. A couple of years ago, I performed sleeve surgery on my Ariann cardigan knit with Brooks Farm Yarns Mas-Acero. The sleeves were started at the wrist and then joined to the body and knit up to the neck. It was hard to know exactly how long the sleeves should be before joining, and the yarn was especially soft and drapey.
The finished sleeves were easily two inches too long. Do you know that you cannot rip knitting from the cast on edge? In order to shorten the sleeves, I had to decide on a row where the ribbing should start if worked downward. Then I snipped the yarn in that row, and pulled out the row, one stitch at a time, detaching the extra length. (Sorry I do not have photos of the actual surgery. This was over two years ago -- long before I was blogging.) I did save the detached sleeve pieces. They are like my red badge of courage.
I have good news on my latest sweater fiasco -- the fuzz ball Cerisara. I used ALL of these de-fuzzers.
It took a lot of time, but the stitch pattern shows again. And my "Evergreen" Cerisara, in Handwerks So-Soft DK, is now a finished object!
I hope that all of your knitting (or whatever is your work or passion) goes well, and that your mistakes will be few and far between!