Hi Charly,
An interesting concept. And boys will be boys so it would explain some of the damage to the blades. I hadn't actually thought about that possibility. It would mean a lot of children running around with swords.
One thought is that the most prevalent sword smiths had small hands, and everyone else copied their design.
With my grip size I can effectively hold a sword grip that is 10 cm (an uncommon grip length for a DA sword), even with the flat pommel and flat cross. However you are very limited in how you can hit, and the style parallels the Viking Sagas pretty closely.
If you get a chance to read the sagas you will notice the Vikings don't do a lot of blows, but look for an opening and then do a solid hit. I believe this is due to the fact that your hand is locked in position i.e.; your wrist can't rotate vertically, only rotate laterally (which you'd never do).
A lot of my customers ask for the 12 cm (extremely rare) grip length so that they can utilise the "fighting manuals" that have become so popular of late.
Regards Charles