Hi Thomas,
you are right, this is a converted Pocketwatch. The movement is a caliber 52
dating to 1895. The movement was taken from a lepine type watch, that means
winding stem - crown at 12 o'clock, small seconds at 6 o'clock position. The
hand setting mechanism is realized with the pin at 1 o'clock position (moved
to 4 at your watch). To use the lepine type movement in a wristwatch case and
have the winding crown at 3 o'clock a new dial has ben created (not by IWC)
that of course moves the small second sub dial to the wrong position at 9
o'clock.
The movement is surely original IWC, but the case the dial and the hands are
not original. You can find a lot of this "marriage" type watches taht use
pocket watch movements in a custom made oversize wrist watch case on a famous
online auction platform.
For collectors the watch has no value since it is not made by IWC. For others
it has at least the value of the pocket watch movement. If you have inhertited
maybe it has sentimental value to you.
The caliber 52 was the workhorse movement of IWC at that time, which means it
is not rare.
br
Cromagnonman