Overseas real estate and other holdings was generally immune to that - in some cases you wouldn't even be able to hand it over to the occupying gov't if you wanted to (since the country with the wealth was hostile to that occupying gov't), in other cases property seized that way was returned through legal means, again through the judiciary of the country where the assets reside, as any contract or transfer under duress is illegitimate and the transfer is reversible.

It being in the vault or at least on an audit trail of some other institution who can later vouch about who seized it, as court evidence.

I doubt that'd work during a war. The best you can hope for is that your country wins and you can collect reparations.

Focus on getting your ass out of there and forget about your assets. Value of an asset to you is zero if you're dead.