PS:
And did I read between the lines correctly: This is rather a candidate for a belt axe and would be an ´emergency Tomahawk´ at best or not even that? (its weight is 17 oz)
This would help me to design a properly shaped handle. Because my desire for a Tomahawk might lead me on to wrong paths. 
"Tomahawk" is a rather elastic word, both then and now, I think - it originally meant a war club, and the word was stretched to include small trade hatchets of various types. There really isn't a good dividing line between a "belt axe" and a "tomahawk," and folks generally refer to any small axe that isn't an "American pattern" (the rectangular design that became the standard for modern axes) and can be traced to the Indians or the frontier as a "tomahawk. If you are thinking of a belt axe as a tool and a tomahawk as a weapon, it is likely that small axes of that size often served as either as the need arose.
Apart from the wedged eye (and I don't actually know for certain how the original eyes were shaped), your axe most closely resembles a 17th or early 18th century style hatchet/tomahawk, in both profile and cross-section. There aren't many repros out there with that wedged shape. It would be quite appropriate for the Beaver Wars, King Phillip's War, King William's War, and maybe Queen Ann's War. It would be somewhat less appropriate for the longrifle period, but I'm not sure how long that style continued to be made. I believe those were used as both tools and weapons, as far as anyone knows. There are very few replicas of that design being made today, BTW.
By the mid-18th century there are more varieties to choose from - the American Pattern felling axe probably originates around that time, and hatchet-sized variants start showing up by the 1770s, I think. Those are primarily tools, though they were sometimes used as weapons (see Bob Benge' hatchet I posted in the Antique Accouterments for one that was used as a weapon). On the other side of the spectrum, you have spike, pipe, spontoon, and pipe-spontoon tomahawks hawks which are primarily weapons and secondarily tools (notably, the spontoon variants have no utility as tools at all). I think round-poll tomahawks continued to be used into the 19th century, though the design changed to have more concavity between the cheek and the eye.
Axes in the 18th century, regardless of size or design, almost invariably had straight handles - the single exception I know of has a handle with a simple curve away from the bit, quite unlike a modern handle. Not much difference between a tool and a weapon except for maybe a few inches of length.
Weight-wise fits right in the middle of the pack - there are a lot of much lighter examples, mostly of the spike and pipe tomahawk variety, illustrated in Neumann, but there are examples are notably heavier, even of the pipe tomahawk variety. As for classifying it as an "emergency" only weapon, well, for a dedicated fighting axe I personally probably would prefer a lighter head. However, a one-pound head isn't notably overweight, and in practice I suspect that it wouldn't make that much of a difference under the conditions it would realistically be employed. Ergo, I think that it would make a perfectly acceptable weapon if you needed one, certainly much better than a felling axe.
