I always thought that it was another name for Tyr (Tiwas), and that his name came from the word seax (like sax in Swedish, a kind of knife), and that the Sae were named for him. Anyhow,I am not so good at Saxon relgion, so I looked it up and found this, which is somewhat different, but non the less, interesting:
"Seaxnéat is only mentioned in a couple of sources, and therefore is very much an enigma. He is recorded as an ancestor of kings in the genealogies of Essex. When the Heathen Saxons on the continent were forced to renounce their religion and accept baptism, Seaxnéat or Seaxnéat was one of the Gods they had to renounce. It is thought the Saxons took their name from the seax, a short sword, not unlike a large Bowie knife. It would therefore go that the Gods name means something like sword god or sword friend. Many have taken him to be either Tiw or Ing, but it is entirely possible Seaxnéat is a God in his own right."
I think it's interesting, as a lot asatruar still to this day carry a scamaseax as part of their attire (the same way a sikh carries a dagger). I had always assumed that this was becaus the Havamal says that a man should always keep his weapon by his side, because you never know when he might need it. Well, it is interesting then, that it should be a seax in particular, and not just any knife. Maybe that's a throwback to this? Hmmm...I see an essay paper in the making...
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