These look great! I love the style! Would you be able to enter my weapon/armor/shield design contest at all? The winning designs will be usable in my game that is currently in developmentchi-u.deviantart.com/journal/M…
Without any scale these look like daggers, really. that's what I thought until I read the description.
I think that happens because of their length to width ratio, since the brain works on the assumption that the width of the blade is that of a real weapon, e.g. 3-4 inches, and calculates the length based on that, which makes it 15-20 inches - a shortsword at most, even though the handle appears too thin in this case.
Overall, there's no point in increasing the mass of the weapon, unless it's blunt weapon - you can cut with a narrow sword as well (if not better - think katana) as with a wide one.