That is, an individual holder or investor decides that instead of writing down the actual words, it would be better to use hand-drawn symbols or images that only them can decode.
What do you think?
There's no standard to it so if you ever forgot how you encoded your words into pictogram, you're screwed.
On the other hand, if it's too simple, it wont do anything because a thief will still think that it's important and will most likely get that it's representing a seed phrase.
So, stick to the standards like using words and a separate "
BIP39 passphrase",
Even if you forgot, the words may not be useful on its own but once you seek technical advise why it's empty, someone will likely say that "
it might have a passphrase"
which can lead you to seek for your separate backup or even from faint memory, there may be a chance to bruteforce the correct passphrase.