Currently it does not seem possible to select multiple tabs and then act on them such as clos, bookmark or move them to a different named window/profile. This means that if I want to merge two named windows I have to move tabs one by one, which becomes impractical if one has too many tabs open.
Selecting multiple tabs, using Cmd for sparse selections and Shift for continuous selections should be a feature.
In Safari it is possible to select individual tabs with Cmd held down, or select an entire range with the Shift key held down.
The same is possible in Arc, using the same keys.