Severance offer, what should I ask for? - 7 months and counting

I was offered 18 weeks of severance after 18 years as a bookkeeper, and I have a few days to sign. I worked as a bookkeeper before this. There is a non-disparagement clause. Should I see a lawyer?

Ask for the offer in writing and do not sign on the spot. A day or two to think is normal.

An hour with an employment lawyer cost me a small fee and made me feel much safer about signing.