2-Factor Unlock & Fragile Versions
What I'm looking for is a glass/ceramic ring that I can snap with a fair impact and couple to an encryption key.
This should pair as half of an encryption key to add the kind of security necessary for encryption to be effective while enabling short memorable passwords.
Additionally a fragile/destructable model would be a lucrative business offering. Obviously, it would only be ethical if it were advertised as such. And certainly it should be. Catering to the "security minded" such a variant would enable one to transform a device bearing a short key instantly into a device bearing a long key.
With the full key backed up in a secure location one needn't risk either coercion, loss of the NFC ring, or loss of data.
You can't beat the repeat sales. One might say such customers are literally asking for it. However, if you decide such a model is worth a markup, you ought to post a bounty for a repeatable reconstruction of such a key in order to back up the notion that such a device is worth what you might ask.
I think the most critical factor in keeping the ring from being falsely persuaded to deliver is a time based one time password from the device to be unlocked. That, however might be beyond the scope of this device.