[Geo99]

David,

Mauser made pocket pistols from 1910 to about 1941, in both .25ACP and .32ACP. What you said "1/2 of these guns have rust blued triggers,etc ....and 1/2 came with fire/blue triggers" is incorrect. You may want to study up a little before you buy one to make sure you get what you want.

There are 3 different main models (many sub-models) of the Mauser pocket guns.
All Mod. 1910 have fire blue trigger, ejector, take down, and slide release up until 1936.
All Mod. 1914 have fire blue trigger, ejector, take down, and slide release up until 1929. Then the finish changed to salt blued, up through 1933.
All Mod 1934 have salt blued finish on the frame and all small parts.

None of them have rust blued triggers, but when they wear & age the fire blue can often fade to gray metal, which you might mistake for a rust blue.

I don't quite know what you mean by a WWI model, but obviously some of the guns made up until 1918 could have been used in WWI.

Hope this helps,

- Geo