Edit: if your question is “how does this technically look in practice”, here is an example: [1]

[1] https://github.com/niftyhorde/swap.kiwi/blob/master/contract...

Please tell me how Ethereum solves the problem of exchanging WoW gold for FF14 Gil in a trust less manner.

The problem of transferring digital goods controlled by the same entity in a trust less manner is trivial and solved by many technologies predating Bitcoin. I can already trustlessly sell a piece of copper in World of Warcraft for gold without involving any other third party.

> I can already trustlessly sell a piece of copper in World of Warcraft for gold without involving any other third party.

In this case the third party is Blizzard Entertainment, who can control the state and data.

And in the case of two Ethereum based assets, the third party is the Ethereum network, which can be forked to control the state and data (as it was after the DAO fiasco).

ETH Classic still exists, but the community came to the agreement that forking was the best way to deal with the issue. The only person who lost on that agreement was the hacker. Where as Blizzard can do whatever it wants. Surely you can see how a forked blockchain was a more democratic process than a centralized database.

A successful fork requires a consensus across the majority of developers and users in the network.