Here's some more info on the Seax that I found on myarmoury.com that you might find of interest (the last link has a number of artifact pictures):

Sax (or Seax)
A large war knife with a blade having a straight back, a single cutting edge, and a point of varying shape. In many cases the grip was set slightly to the rear, toward the back of the blade. Its size varied a great deal, ranging from that of a dagger (about 12-16") to that of a sword (33-40"). This large knife-which is regions north of the Alps was used as a domestic implement, a weapon of war (a scramasax), and, according to some experts, as a throwing weapon-derived from a very similar weapon made of bronze and widely used in the Hallstatt period (900-500 B.C.) to the beginning of the Christian era) in an iron version. It was one of the national weapons of the Saxons, who at the time of the migrations (4th-6th centuries) carried it in a sheath on their left side and, at least up until the early Middle Ages, alongside the sword. Examples have been unearthed in the warrior tombs of various Germanic people, which clearly shows its wise distribution.

With the advent of cavalry, the large sax disappeared from the warrior's armament and was relegated to the task of a domestic implement; the smallest type became a knife, which, together with the sword and the spear, was part of the horseman's weaponry in the field. In an intermediate version it survived throughout the Middle Ages as a hunting knife.

Scramasax (or Scramaseax)
A term used for the first time by Gregory of Tours (6th century), and later in various Visigoth legislative documents which lists weapons and includes the scramasax among the weapons issued to warriors. The etymology of the word (scrama, causing injury, and sax, [war] knife) suggests that it was a particularly offensive type of sax. But the precise meaning of the term is unclear.

http://www.myarmoury.com/feature_euroedge.html#sax

The Anglo Saxon Broken Back Seax:
http://www.myarmoury.com/feature_seax.html