I'm absolutely in agreement, that the actual dimensions do need to be catalogued carefully, its part of what I've been doing with the existing examples that I've been studying.
The thing that they show clearly is a huge range of dimensions - the cluny falchion is pretty small, the milan and conyers much larger. Thorpe is noticably longer than the Castillon hoard example, and so on.
I've attached an image of some of the ones I've got data on, and one or two which are estimates based photographs (those are marked with an asterisk)
In all cases, the primary cutting edge is that facing downwards.
Each one of these falchions should, when I'm finished, have a full data sheet with distal profiles, and full photography.
(Though I'm actually tempted for my work to also do shaded line drawings, having recently been astounded by the linework in Viollet le Duc's "Dictionnaire raisonné du mobilier français de l'époque carlovingienne à la renaissance" - the clarity of line is, in my opinion, far better in those 140-year old illustrations than the photography in many modern books, and its the sort of standard of presentation I'd like to aspire to. )
Here's the pic:
