That's a style of knife, like the Moras and puukkos, that's been used for centuries by people who managed to retain their fingers despite the lack of a guard.
I've got one of the last of the large Cullodens. When I see what the street price on the Brave Heart might be, I'll probably pick one up. Although I can't see using it for its traditional purpose, no matter how effective it is at it -- stabbing.