Nope, just keep you seed safe and that's everything you need. Seed gives you ALL of your private keys.
Thanks. I asked about the private key because CryptoSteel doesn't support 32 words in Decred seed (it supports only 24 words), but it does support hex or base64 keys. So, is it possible to extract private key from Decredition wallet to save in CryptoSteel? Separately, can you please confirm that only the seed is required and not the passphrase (or the wallet password) for recovering a wallet.
The seed IS the wallet. That is all that is needed to recover your wallet. Never heard of CryptoSteel, but no you cannot extract private keys in decrediton. We have no plans on ever adding that as well.