The blades do tend to be fairly short but longer than you would imagine as they too are curved.
This is one of those comically out of touch armchair historian takes.
Curved blades were made back then for the same reason they are still made. They are effective at killing other humans quickly. Aimed at a throat or other vulnerable point the blade is highly likely to drag across an artery on the withdrawal thereby quickly ending your confrontation.
Curved blades don't work as well on animals with fur and thick hides.
(source: I'm from the region)
I imagine the focus on the scabbard is partly because it was largely decorative and served a very different function - such as being collateral.
So all parts of the blade were important, but the part "used" the most has highest investment. If you don't draw the knife, then it gets most use by having obvious skill in its crafting.
I was hoping to find out why they have that shape and the "many nuances" of the design.
