ETHPOW or ETHW is the token that will emerge if there is a fork of the Ethereum blockchain. During the Merge, some community members may disagree (e.g. want to stay with the Proof of Work mechanism) and fork ETH. What they may do, is "copy and paste" the Ethereum blockchain. The result of this is there would be 2 blockchains and 2 tokens. There would be the existing Ethereum blockchain that goes through the Merge with the ETH token. And then there would be the forked chain with a new token called ETHPOW or ETHW.