It's all very well to use multi-factor authentication, but supposing you want to 'destroy a factor' so that in an situation where you are likely to be coerced to provide your passphrase, you can happily turn it over while smugly informing the attacker that it will do them no good because the physical token is 'dead'?
Does anyone manufacture hardware tokens which do not require physical strength in order to quickly 'destroy' them (ie. zero out the private key) when the user is under duress?