Somewhere I thought I found that the "Victorinox Waiter Plus" is a 91mm. Here is shows it as an 84mm but says it has a removable pen. Are there 84mm's that can accommodate a removable pen?
http://sakselector.info/cgi-bin/sak_selector.cgi?model=waiter_plus&buy=1&metric=1&pictures=1
There is a Waiter Plus, and it is 91mm, and it has a pen. The page you link to has model number 1.3305 which is the model number for the 91mm Waiter Plus, so the "84mm" is a typo.
No 84mm plus scales exist from the factory, although some folks have known to mod 84mm scales to hold a pen.