It's called "perspective".
Ah perspective. A sly beast, innit?
I was going to say that at first, but even then the sword looks a bit short. Though it could just be due to a lack of color and shading. Sometimes a shadow can add a heck of a lot of depth, size.
Its what I was thinking too. Even with it just being the angle of the shot, it looks to me like the blade'll be a regular long sword at most. But it could just be the lack of coloring.
Morgan himself looks pretty bad ass though, eh?