So I did
importprivkey "private_key_from_weak_brainwallet"
in my bitcoin core console.
I know it's a weak key but it was for testing purpose only (1mBTC)
Now, is it possible that the wallet *ever* use this address again as a change address?
Because I don't want this address being used ever again since it's weak.
I thought I better change my mind and *export* the key, but I there doesn't seem to be an option for it.
So, edit with pywallet? Or just create a new wallet and make a transaction to it? Or just don't worry?
If you enable the coin-control features of the wallet, then you would have the opportunity to "accidentally" choose that address for the change output if you choose to specify a change output address. However, the wallet should not automatically choose that address if you don't specify it.
As a suggestion in case you want to do something like this in the future:
I probably would have created a backup of the wallet before importing the private key, and then used coin-control to spend that specific output sending it to some other address under my control. Then I could just recover the backup and the imported private key would be gone (since it wasn't there when the backup was created.
