Dark souls has made it so I think its a greatsword and its pretty hard to change something so burned into my mind from hundreds of "greatsword" using hours in dark souls
A casual flip through the pages of Hans Toloffer's guides to combat will answer your question. The warden uses a longsword. And much of the combat, stances and techniques, used in for honor can be found in those pages. Fun reading.
They hold a bastard sword or long sword which was common amongst medieval knights
[url=https://en.m.wikipedia.org/wiki/Classification_of_swords]But want to classify the sword yourself because you can't believe a person on the internet?[/url]