Editing manually the velocity in the volume column can be a tough time consuming experience for whom who use VSTi.
The editing menu at the right of the tracks has really limited options.
To increase the possibilities, an editing panel could be associated to each track. It will allow to draw a curve (like in the automation panel for volume) and hard copy the value of the curve to the volume column(s) by clicking on a bouton “Apply the curve to the volume column”, for exemple.
Several people have written tools to do that, in various ways. However, in redux, therefore eventually in renoise, there will be a ‘note properties’ kind of function, with sliders for all note values like vel., pan. and del., whether this will work for a selection as well is not yet known.
A few tools I wrote along those lines:
Individual notes:
http://www.renoise.com/tools/note-properties
Using Automation lanes:
https://forum.renoise.com/t/new-tool-2-8-velocity-pan-delay-automation/39441
Setting selection in pattern:
https://forum.renoise.com/t/new-tool-set-meta-values/33933
I agree this really needs addressing natively in renoise.