I have a question about Nano Wallet:

For Simple Wallets the wlt-File will contain the encrypted private keys. That makes sense to me.

For Brain Wallets the wlt-File does not store the private keys, as they are always derived by the passphrase. It also states on the NEM homepage, that a wlt-File is not needed. However, when I log in with the Nano Wallet Desktop Client, it always requires a wlt-File.

On the other hand you would never need a wlt-File if you back up your private keys, as you could always just create a new wlt-File with the "Private Key Wallet" option within the Nano Wallet Desktop Client. In this case you would (as I understood it) have a new wlt-File with an encrypted private key (same behaviour as Simple Wallets).

And of course you can always create a new wlt-File with the Brain Wallet option, chose any name for the wallet you like, and use the same passphrase (from an existing Brain Wallet). I tried this, and I could login as expected, however the wlt-File had different content (I used a different wallet name)...so the content cannot be based on the password alone...perhaps the wallet name makes a difference, perhaps the creation date...but I could not resolve this.

Does anybody know what the wlt-File actually stores when you create a Brain Wallet?

I could not find any precise information on this.