Ability to edit page in-situ, rather than through a separate block interface. Previously discussed options:
drag-and-drop style method to add blocks from sidebar, then edit them in-page (which would largely make the water-weasel pane into a block-selector pane instead), or "+" buttons in the page that open a block picker
consider not replacing water weasel but leaving it intact as an alternate editing experience
or ability to 'flip over' or 'open settings' for a block to get at 'extra' settings that are not convenient to edit graphically
Ability to edit page in-situ, rather than through a separate block interface. Previously discussed options: