Where do you keep the titanium plate? I'd be more worried about losing it due to a natural disaster than merely having it destroyed beyond readability in a natural disaster.
What happens if there's a typo in the engraving? Who's doing the engraving? How much do you trust the people you are providing the key to do it? When does the paranoia kick in vs being diligent?
This was at least an innovation in the bitcoin community. Several assemble at home systems where you can build a physical manifestation of a secret. Metal cards you punch with a hammer and nail. Another is essentially a tube where you string along metal letters of the password.
Sure, sounds perfect. Let me send some crypto person that has invested in a home stamping kit the secret to my crypto wallet. At least they won't know what it's for to be able to hijack my wallet. phew. had me nervous that committing the cardinal sin of sharing my secret with someone I don't know isn't going to come back to haunt me.