faenzaiconslibreoffice
According to a WEB UPD8 post from july 2011, it is possible to install Faenza-styled icons on LibreOffice toolbar.
I can't install Faenza the traditional way on LO 3.5 (i.e., changing the toolbar icons from Crystal or Tango from inside the application's "Options" menu) and now those icons are broken.
Faenza was already installed but the update removed everything.
You have the tango icon theme selected (this not a legacy Open-Office theme by the way). Also I found that LibreOffice seems to force certain themes if your GTK+ theme is changed (at least in 3.4, so they might have back ported that to 3.3.3).
What you can do is go to tools>options>view and choose another theme (such as galaxy). If you don't have that theme, then you need to install the other LibreOffice icon themes (called styles) from the Software Centre or synaptic.
You can get the Sifr icon set (very similar to the Faenza set depicted in another answer):
Much more simply by using the PPA available for Ubuntu 14.04:
sudo apt-get install libreoffice-style-sifr
To chose this icon set, then go to Tools > Options > LibreOffice > View and then select "Sifr" under "Icon size and style" drop-down.
Best Answer
Update manager, today updated LO to 3.5 also here (Ubuntu 11.04). As I was using same icon theme I noticed same issue.
Just copying faenza archive over /usr/share/libreoffice/share/config/images_crystal.zip was not enough. Comparing icon theme archives from LO 3.5 with faenza set, revealed two possible misplacements:
I expect that first one was responsible for this issues, although I changed both: download link (3.6 MB)
So after downloading this archive place it as /usr/share/libreoffice/share/config/images_crystal.zip and then setting view to crystal should show faenza icons again :)