Hello Panda,
In the Bender book, the caption under the photo of this tool indicates this was an amourer's tool. Bender does not specifically say it was used for lugers. But the two-side screwdriver blades seem to be the right size for grip screws and for the firing pin retainer...
Regards,
Pete... <img border="0" alt="[typing]" title="" src="graemlins/yltype.gif" />