I hate when that happens. If no heavy diagonal cutters I score a line with an exacto knife 4 or 5 times and snap off with a pair of pliers.
Then a little touchup with a sanding block. I hate breaking tools. I still have a pair of Thomas and Betts crimpers that I bought in 1983 and crimped countless thousands of connections when I was a car stereo installer. They have quite a patina on them but work as they did when they were new. Limitations.