Deciphering a swordblade inscription

[Duncan Head]

See http://britishlibrary.typepad.co.uk/digitisedmanuscripts/2015/08/help-us-decipher-this-inscription.html#

Anyone want to have a go?

[Erpingham]

Other than it is probably religious and at least partly abbreviated Latin, I wouldn't know how to start.  I'd also go for a German origin (based on an apparent Northern European distribution) rather than any of the exotic suggestions in the comments.

For more fun trying to work out what these swords mean, try http://www.myarmoury.com/talk/viewtopic.php?t=32096