For a seax to look 'right' to you, you must have a good understanding of what real seaxs looked like. Google "historic seax". Look carefully at the drawings and photos of old seaxs from 1000 years ago or so. Ignore the modern reproductions, which are usually poor interpretations of the real thing. Keep in mind that the old seaxs we have today are badly rusted, which has affected the profile of some, and they are sometimes well used blades, which means they may have been sharpened until the tip has been move up.
To my eye a seax and a bowie are very different. If your drawings of a seax look like a bowie, you are probably drawing a bowie-like blade.
A seax is more than a single edged knife with a straight, unsharpened clip. 1) The seax has no plunge. The blade bevel continues into the entire tang, something like a Pukko with a triangular cross section. 2) Some seaxs have their greatest width at the end of the front 'clip' and taper either steeply or almost imperceptively toward the tang, which produces the 'broken back' profile. Some seaxs are straight, although these tend to be the longer ones. 3) Seaxs range in length from a handy edc blade up to sword length. The longer ones were weapons, not tools. They were designed to penetrate riveted chain mail. So they had strong points and relatively thick spines. 4) To my mind a seax never has a guard. You go straight from blade to handle. (Some people include guarded knives as seaxs because they call every old, northern European single edged knife a seax. I disagree.) 5) A bowie edge starts basically straight from the tang and, about 3/4 of the way down the blade, it curves up to the tip. The curve looks like it can be used for skinning and it has belly. A seax is essentially a straight blade. The tip is almost never above the center of the blade and usually is well below the center of the blade. If there is a curve to the edge near the tip, the curve is gradual and has no belly. 6) A seax can have a steep clip or a long, gradual clip. But the clip will be straight or curve down. The clip will never curve up like some bowies.
The definition of any knife style is fuzzy. There are no 'standards'. Still, if it is a recognizable style, there will be common features. I have given you my definition of a seax. Feel free to define it for yourself.
By the way, the Franks supposedly got their name from the "francisca", a small ax or hatchet. Just before charging an enemy they threw their franciscas to disrupt a line of enemy warriors or a shield wall. The Saxons supposedly got their name because they loved to fight with the seax.
