[Kromm]

There is no "precedent" set here. Melee Weapon skills are necessarily sorted out on a case-by-case basis. There are so many weird and wonderful weapons to shoehorn into a finite skill list (which some would say is too long already!) that each skill effectively becomes a collection of special cases that bear very little on every other skill.

Knife differs meaningfully from Main-Gauche because it's the general skill of cutting and stabbing with very short, one-handed blades and not the specific skill of fencing with the subset of knives suitable for parrying. Tonfa differs meaningfully from Shortsword because it covers side-handle batons that can be spun and used to hook, not short blades and sticks held at one end. However, just as Main-Gauche covers some (but not all) Knife weapons, Tonfa covers some (but not all) Shortsword weapons; in particular, since it covers all means of fighting with a tonfa, including swinging it like an ordinary baton, it logically encompasses ordinary batons.