// file: SettingsPageForm.ui.qml
Item {

    property int clickIndex: -1
    // ....

    ListView {
        // ...
        model: dbSettingsModel

        delegate:  Item {
            // UI graphics stuff with model.name, model,value etc...
            // ...
            // the delegate sets the index, the handler will reset it to -1
            MouseArea { onClicked: clickIndex = model.index }
        }
    }


}

The implementation logic watches for the change signal:

// file: settingsPage.qml
SettingsPageForm {

    ...

    function launchEditor( index )
    {
        // getRole( row, roleName) was added to C++ model because 
        // model properties are available inside the delegate only
        editor.title =    dbSettingsModel.getRole( index, "name"     )
        editor.value =    dbSettingsModel.getRole( index, "value"    )
        editor.unit =     dbSettingsModel.getRole( index, "unit"     )
        editor.minValue = dbSettingsModel.getRole( index, "minValue" )
        editor.maxValue = dbSettingsModel.getRole( index, "maxValue" )
        editor.open()
    }

    onClickIndexChanged:  {
        if ( clickIndex >= 0 )
            launchEditor( clickIndex )
        clickIndex = -1
    }
}

I found no other way but to expand the C++ model (dbSettingsModel) with getRole( index, roleName), as model properties are not available outside delegates.
Overall it works, but I feel I'm overcomplicating it, I fell there must be a much cleaner way taking advantage of delegates straight inside UI deisgner.