In KeePass 2.18 you can select multiple entries, but when you try to edit them, all but one are deselected.
Here is how a "multi-edit" could work:
If multiple entries are selected for edit, the usual field value is displayed if all selected entries have that value in the field being displayed.
If there are different values, either "<several values>" or a list of values is displayed (For real-life examples, see meta-data edit in foobar2000, or meta-data edit in Adobe Lightroom).
So if I change a value, all selected entries will update the correspondig fierld to that value on save. Values not touched will keep their individual values on save.
Why I wish for it: After having imported about 250 passwords from the browser, none of the new entries has a title. The first column (title) is blank, and it looks strange to have to double-click empty space to open the corresponding entry.
When implementing multi-edit, hava a look at foobar2000: I simply feel it was done right there, and I wonder how anybody could do it wrong.