Segovia is a bit cooler than Toledo on average in winter, quite a bit cooler in summer. I’d say only needing a light jacket in Toledo in winter was probably a bit unusual, as the low is typically around freezing.
I may be biased on Segovia (and in favor of Barcelona, since it’s my favorite city) - I have only visited once, for a weekend in college while studying abroad in Toledo. It was February, and the place I stayed turned out not to have heat (did not know that was a question that needed asking!!) so I wore all the clothes I had with me to sleep in and still shivered all night. Segovia is lovely and Salamanca and Avila are not far away. I just think Barcelona is worth a longer stay since you’ve barely been! Plus should be better weather there for lots of sightseeing.