Why would anyone assume the risk to put a gun to your head when they know you can't give them what they want just by yourself? With blockchain you can prove them that's the case. They would have to also put a gun to the head of the cosigner(s) in order to get it.
I am not aware of any other mechanism similar to BTCs multisig that doesn't require a trusted third party.
I am not aware of any other mechanism similar to BTCs multisig that doesn't require a trusted third party.