I hesitate to suggest how to grind yours. I did a seax earlier this year. I matched the profile of one in a British museum. The blade was only 9" and that was one of the bigger ones. The broken back on mine was closer to the middle. The grind is simple but interesting. You do a full flat holding the edge level. The spine ends up thickest where the break in the spine is, so you get a taper in both directions, towards the tip and towards the handle. I'm not sure about the fuller as mine didn't have one. One way would be to grind in the fuller, then ignore it and do the grind I described (full flat to the spine). That's if you don't want a shorter more abrupt bevel.