Bip39 Brute Force. Theoretically, you can Feel out the mnemonic phrase by his own, but it is not Harmless, due to the fact a human can't do an awesome task with the random generation. The best way to safe one’s wallet will be to take a mnemonic phrase created by https://iowa-bookmarks.com/story14232704/bip39-mnemonic-phrase-tool-top-guidelines-of-12-word-seed-phrase-generator