N2S -
Yes, some of the styles (for seaxes appear to come in quite a variety of forms, not surprisingly) do look sort of like Bowie knives, particularly perhaps (f) from below?:
I would assume that seaxes are actually one of the ancestors of Bowie knives, assuming that English (and German(ic)?) settlers in the American colonies brought some 'traditional' knives with them, some of which would have descended from the seax-form.
Yvsa -
Actually, if you look at the one modern seax that sweet posted, it does seem to have a 'mini' guard. However, from the 'period' seaxes, all of them (or most of them at least) seem to lack guards. There seem to be various ways, elegant and simple too as you point out, of 'solving' this 'problem'. One is the widening of the handle at the base where it joins the blade. Some of them also seem to have curved handles (which is what I assume you mean by 'reverse swelled'?) like some khukuris. And I notice one of the forms seems to resemble a meat clever, so that the back of the blade itself, by extending past the base of the handle, prevents hand-slipping.
On the fullers, I wonder about this too. ON the one you posted, the 'fuller' seems to be in the equivalent place to the
aunlo bal (Nepali for 'finger of strength', as JP tells me is (one of) the correct term(s) for the 'blood-gutter' on a kukri). I don't know if the
aunlo bal serves any functional purpose on a khukuri? And on later mediaeval broad-swords and the like, there is usually a fuller running down the middle of the blade, but sometimes it is rather narrow (and non-functional perhaps?). I don't know. Is there a (functional) purpose other than lightening/strengthening a blade for 'grooves' in a blade?