Re: Acceptable?
I think it should be pointed out that we weren't really arming Johnny-Prussian in 1914. Although there were a few embarassing things that it turned out only they supplied (when they suddenly stopped), such as khaki dye for uniforms. Admittedly almost everybody else who had dreadnoughts seems to have got them from us, such as Austria-Hungary (so good they named it twice).
So it wasn't so much the arms dealers, as the governments buying so many that caused that. Plus a horrible miscalculation on what modern war would be like. And a German (and Austro-Hungarian) political leadership who were both hilariously incompetent and dangerously belligerant. With dishonourable mentions to the pisspoor diplomacy of Grey for Britain and the Russians.
On the other hand, Britain did rather insist on its right to arm the South in the US Civil War - because just because they were fighting to retain slavery was no reason not to take their money obviously...
Biting the hand that feeds IT
