Still doing as much reading as possible, but thanks to a kind chap on a more European oriented forum, I was pointed to this sword that Christies auctioned off. Mid 14th century, same type of cross, same type of incised lines. Similar blade profile.
http://www.armsandarmourforum.com/fo...der-the-hammer
A photo of the mark attached here as well for forum archives. There are other examples as well I am finding, some with the double circles as in this case.
In light of this, I can only say I think Lee (and Jim) have been spot on and I am quite happy about being able to realistically say I think my example should date mid to late 14th century.