I never encrypted it.
Is it an online hot wallet? If so, I wouldn't use it to replace a Trezor.
For cold storage, I find Electrum easier for offline signing than Bitcoin Core (read
my sweep method to get an idea).
So I suppose I can make a long passhrase.
abcdefgh87654321HGFEDCBA
abcdefgh and 87654321 are
very easy for a (dictionary) attack.
Then make 5 backups of the wallet.
Make them on different storage media: different brand USB stick, HDD or even CDrom. If one of them has a limited shelf life, another one might last longer.
Then test the backups of your wallet!
I WOULD guess that is safer than a hardware wallet.
It's a lot more difficult. How about a combination of both: offline signing with Electrum connected to a hardware wallet?
Also should I upgrade to core 30 or stay on core 29
Or use core 28.
As far as I know, they're all safe. I'm still using an older version.