Honestly, this is more of a problem for blockchain than it is for the old system. Let's say that an 80's movie villain gets his goons to beat you until you sign over the deed to your house (he wants to open another dojo). Today, you could go to court, present your evidence that you made the transaction under duress, and you get your house back. Even if he won't sign the deed back to you, the court can just print a new one on a laser printer, give it a fancy stamp, and the house is yours again.

In the blockchain world, there's two options. The first is the "code is law" option. Since you sent him the house, it's his and there's nothing you can do about it. The court might arrest him, but there's no way of ever recovering your house. If he's particularly spiteful, the villain might kill himself. With proper security, his private key is lost forever and that property becomes inaccessibly for eternity.

The other option is the "reasonable" option. Here, you go to court and have his token for your house officially invalidated. Additionally, a new token is minted for the property is minted and sent to your account, making you whole again. However, this only works with a modified blockchain that allows a centralised authority to invalidate and mint new tokens. Since we're already trusting this centralised authority, then we're back to the old laser printer and stamp, just with extra steps.