Generally we see the Empire using 'Panzerkampfwagen III's which were designed between 1935-37. This is a decade ahead of the time period Youjo Senki takes place in. We also see aircraft that appear to be Junkers Ju 87's in the manga which were used in 1936 (in the anime they at least use biplanes, in the manga we see WW1 bombers in heavy use).
Then of course, you have the service rifle the flight mages use which look like either the Gewehr 41 or Gewehr 43's (most likely the 43 based on appearance and mounted scopes). Which, as the number indicates are 1941 - 1943 semi-auto rifles...
The flight mages also use MG34s as their "beam cannons". (1934 LMG) =P
Yes, the equipment is completely off of the doctrine they try to depict, why they would have trench warfare problems when they have tanks and dive bombers is beyond me. Its like someone power teched their small arms and tanks without updating their doctrine tech in a strategy game (the writer has played games like victoria and hearts of iron).
Anyway, technical details were clearly not though of and instead they probably just used reference material of whatever they figured looked cool from mostly WW2 stuff.
EDIT: Here's a close up of the rifle and LMG they use.
http://vatoto.com/reader#e8e34cf518c6f248_69
Edited by PerfectDeath, 05 May 2017 - 05:06 AM.