I don't think this falls neatly into an Oakeshott type (his classification isn't a general one for all swords, only for the common types of European Medieval swords). One difference between lots of modern replicas and genuine Medieval swords is that modern ones are much more likely to have diamond-section blades, even on the cutting-oriented types that were typically lenticular. Also modern fullers are often much narrower, and terminate before the guard. Since blade section and fuller are major features used to classify into Oakeshott types, it's not so easy to classify replicas.
You could call it Type XVIIIa. Diamond section, shortish fuller, fairly narrow blade without much taper. Perhaps it is meant to be XII, but is diamond-section instead of lenticular.
I like
binary keys (AKA dichotomous keys) for classification. However, they're not very common for classifications of arms. They don't really work well for incomplete classification schemes.