Are you concerned with the failover?
Yes, that's the concern here. I was thinking later on, we can open the meta on the backup master as well after we support opening a region in multiple servers. This way, it will be much fast to fail over an active master change.
As to the weight, basically, it means how many regions to host by a backup master compared to a normal region server. The default is 4, i.e. by default, the number of regions opened on a backup master is 1/4 of the number of regions opened on a normal region server. Should we set the default value to 1 (backup master is treated the same as a normal region server) or a big number (less regions)? If big, how big should be proper?
If we set the weight to 1, it means there is no default behavior change: you can just ignore the new configuration parameter; in the meantime, others can fine-tune it and get more flexibility if needed.