Pre 1891, razors weren't required to have their contry of manufacture on them so it could be from anywhere but a good number came out of Germany so that's probably a good bet. It looks as if the taper is the shape of the blade. It's what is called a smiling blade. I can't see any more hone wear towards the tip of the blade. I think that for 25 euros, you did pretty good. Get it honed and shave with it.
This one is a keeper.
I have a Fontenille with a blade like that and it is my favorite.
I think C. Siemon is either a gentleman that got his name on the razor or more likely a barber or a cuttlery located in Bodenberg.
I have a few french razors that were rebranded like that.
On another forum someone said that the blade lost some metal due to honing... as far I can see its just the type of blade/shape. Anyone can shed some light on this?
I think that smile on the blade is genuine. Not the cause of over-honing.
There are no honing wear at the spine so it would mean tape was used while honing heavily on the toe, which I find very unlikely.
My Fontenille has a similar shape, although not as pronounced. I think your blade was designed that way for comfort.