Probably the expression "brainwallet" is badly chosen anyway. Because a good brainwallet is similarly bad to remember like a complex password. Nevertheless, it might be possible to generate a story around the words so that they become more easily to remember.

Clearly, using a sentence from a book or similar and adding or replacing characters can make the brainwallet harder to break. Combined with a weird and high number of hashing rounds. Even though keys can be collected in each round.

Using a hardware wallet is a good idea for speculation, I think, if you need to store and shift around funds. But also those wallets implement brainwallets / seed sentences. So the difference is not big.

If you are paranoid enough, you would never use a hardware wallet from some manufacturer. Firstly, the hardware can break. Secondly, the hardware can be manipulated. Not necessarily by the manufacturer, but during shipment (except you buy it directly in a shop without providing your identity). Thirdly, the seed sentence can be stolen.

I do not claim, that my code is fast / perfect / bug free. Keep that in mind!

But for a coldwallet, I would claim that a "brainwallet" with a complex passphrase / seed is the best choice. Clearly, it is a method not suitable for the average user. Users should know what they do. And I admit, that I am not fully sure, that everything is implemented correctly. Therefore, the project is open source for erveryone. So that it can be corrected.